Conditioning my Crawl Space…
I live in about a 1600 sq.ft. cape cod style home in Richmond, Virginia. My issue is that the downstairs during the winter is EXTREMELY cold. I have issues keeping the tempterature above 60 degrees during sub freezing days…and the morning after an extremely cold night tends to dip my interior downstairs temperature to the low 50’s. I feel constant drafts in the bottom 3 feet of the downstairs and in some areas around the perimeter walls, i can feel a nice “breeze” around the baseboard. I have older windows, but they do not feel very drafty at all (in fact, i feel the storm windows do a great job preventing air leaks). I’ve completed various projects to try and improve the air flow in the home ( have a attic HVAC unit so all of my registers are in the ceiling) including installation of batt insulation in the crawl space as well as the insertion of an additional return vent downstairs. These things didnt help.
What i’m looking to do next to fix the issue is do a complete conditioning of the crawl space. I’ve gotten quotes to apply 6mil liner for the floor and spray insulation to be applied to all areas of the wall, up and around the rim and sill of the perimeter crawl walls. All vents and holes will be either foamed over or plated with foam board and sprayed over. Because i have no duct work in the floor, i intend to add a blower fan and a couple registers beneath the home to try and pull air from inside the home down into the conditioned crawl to both reach a better temperature equilibrium and eliminate negative crawl pressure issues.
What i’m mainly doing here is asking…will this finally work? The reason i feel their are so many air leaks is because the floor is constructed using planks (it looks like i’m crawling under a deck when under the home) and their was just poor sealing going on around the rim of the home. Are there any other places the air could be sneaking in at the baseboards? should i look elsewhere? If it looks like i’m goign i the right direction, then just give me a thumbs up and i’ll move on.
Thanks ahead of time to all that answer – Brian.
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Replies
Putting the HVAC ducting in the attic (I assume it's an unconditioned, probably vented attic) may have made the pressure imbalance worse, particularly if the ducting isn't thoroughly sealed with mastic or butyl foil tape. And, if the HVAC supply and return ducts are not balanced, that can also imbalance the internal pressures.
The air may be leaking up through the floor, but it may also be leaking through the walls. What kind of insulation do you have in the walls? Fiberglass does almost nothing to reduce air leakage, and walls typically leak under the bottom plate as well.
I would suggest getting an energy auditor with blower door to evaluate the house and the HVAC system before doing anything else. Find out where the leaks are and then you will know what needs to be tightened up.
Sealing and conditioning the crawl space may make a big difference, but that's a very expensive fix if it's not the primary problem.
TO ROBERT:
Thanks for the quick response. The house was remodeled before i purchased it....they put in the central air. How does the location of the HVAC unit cause a pressure issue? i feel all the unit does is pull air in through the returns and blows it out through the vents/registers. i have a least one-two registers in every room. The overall downstairs of the home is very open and there is a lot of room for air to move. The return vent that was added I was told helped balance the pull of air the HVAC unit was trying to pull from the home....was this incorrect? (the new return was placed downstairs around the center of the home, there is a return up and downstairs now).
My house is a full brick home with probably very little insulation....brick runs from the roofline down to the ground. I've seen the old insulation in the walls and some of it in the attic and it's not the greatest (at least it's something).
I'm hesitant to pay for an energy audit as i feel they'll tell me what i already know. Where else could i be getting so much air flow from the perimeter baseboards of the house? Could the Chimney effect only be occuring because of the vented crawlspace? wont the chimney effect be reduced or eliminated if i just seal the crawl? Right now i have a quote to condition the crawl at around 1700....an energy audit was to cost me around 400-450....
I repeat: you are wasting your money without an energy audit with blower door test and duct leakage test.
Air can't be drawn in from the crawlspace unless the same amount of air can exit through the upstairs ceiling (or through walls and partitions into the attic).
If the attic is outside the thermal boundary of the house (insulation in ceiling and vented attic), then any leaks in the supply ducts (all ducts leak, some a lot more than others if they were not carefully sealed) will create a positive pressure in the attic (and waste a lot of hot air) and possibly a negative pressure in the house, which will cause air to stream in from the crawlspace and any other cracks.
If the volume of supply air and return air for the HVAC system is not balanced, by equal size registers and equal pressure drops in the ductwork, then it will create either positive or negative internal pressures which will effect air leakage.
The drafts you feel could be coming from the crawl space or through the walls (very likely from what you describe).
You're only guessing where the problem is. An energy audit will pinpoint the problem and detail the corrective steps necessary.It will be the best money you ever spent.
I agree with what you're saying. It sounds like i definitely have a negative pressure in the house and air is being pulled from somewhere...it's just a matter of where. You're saying that the energy audit can pinpoint the actual location of the leaks.... or, does it just tell me i have greater pressures in some rooms compared to others?
With the amount of air and drafts i feel near the floor of my home, i'm almost afraid of what i may find.
thanks.
Is the foundation brick, block or stone?
What is the height of the crawspace?
Are the floor joists set in masonry pockets at the foundation line or do they sit on a wood sill plate with a band board around the perimeter?
No, it's a matter of where and why.
Yes, a good blower door and duct leakage test will pinpoint the exact leakage areas and also tell you what's causing the pressure imbalance. It may be simply the natural stack effect of the house, but it's almost certainly exacerbated by a poorly designed HVAC system.
There's a good chance that you're not only leaking a lot of cold air but that you're also heating your roof instead of your house. And, if all the supply ducts are in the upstairs ceiling, then there's no way to get heat to the first floor. You have to have supply registers distributed throughout the house.
I understand you’re hesitant to pour more money into an energy audit but it is a great idea. An energy audit (blower door and duct blaster test) will identify all of the issues with the house and the auditor’s report will help you prioritize the next steps. Most likely the crawl space encapsulation will be on the list of items to tackle. In my opinion it’s about air sealing and most of it escapes through the attic. Usually you seal the ducts first, air seal and insulate your attic and then move to the crawl space. You may need to consider a dehumidifier in the crawl once it’s all sealed to circulate the air and keep the humidity down. Good luck!
i'll look into the energy audit again. Thanks to everyone for the help.
as for these questions:
Is the foundation brick, block or stone?
The foundation is Brick
What is the height of the crawspace?
The crawl space varies from 3-4 feet...maybe a tad less in some areas.
Are the floor joists set in masonry pockets at the foundation line or do they sit on a wood sill plate with a band board around the perimeter
I believe there is a wood sill plate. i have never noticed any masonry pockets.
Many times in older homes the floor joist system was set into openings , or wall pockets rather than on a sillplate. This is especially true of homes that are all brick with brick foundations. Even more common in all brick homes with brick foundations and craw spaces. Masons would lay the interior coursing to the bottom of the floor joist height and leave out brick ( usually 2 deep) for the joist end to rest in. Sometimes the floor joists were set and mortared tight at this point and sometimes the joists were left out to be installed later. When joists were installed later by carpenters the tendancy of there being a void at the rafter end was pretty regular. This leaves areas around the floor band line that only have 1 brick to the outside and a gap on the inside of that brick that is never seen. This creates cold spots evenly around the room at the baseboard line that are not easily accessable to seal. Please let us know the results, if you do the energy audit. If you craw into the space and look at the point that the floor joist meet the foundation you should be able to see how this house was built. The solution that I would recommend for this type of situation sometimes involves the removal of baseboard, a few floorboards under the base and floor sheathing or underlayment at each floor joist location to gain access. I hope that this is not the case, but I've seen it many times through the years with full brick foundations.
Good Luck
ROY -
I'll try to take a picture soon and show you what i have. I plan to still do the audit....i will share those results upon completion.
Brian, if you called up a few insulation contractors you just may learn more than having the blower door test at $450. If you do, ask for three quotes, working on sealing and insulating the attic, the walls, doors and windows and then lastly the crawlspace as you have outlined. I would also let them know you have a budget of $5,000 (just pick a number.)
I feel you need onsite eyes and with some quotes you would learn much and may run into a contractor that could really do the job well for a price that works for you now or staged over time.
I am going to disagree and say the energy audit is a going to be a waste of time and money at this point. It's fairly obvious that your crawl space to be sealed, insulated and conditioned AND the HVAC air handler and the bulk of the ductwork needs to be moved there.
It is vitally important to bring the HVAC system within the thermal enclosure. Until you do this your energy use will continue to go through the roof (literally) without achieving satisfactory comfort levels. In a Cape Cod you will find it extremely difficult if not impossible to accomplish this by properly encapsulating the attic around the existing system - though I am sure you will easily find a spray jockey or ten who will be more than happy to try, and cause you a host more problems in the process. With a 3-4 ft crawl you will have plenty of room for a proper installation. In the name of Pele, goddess of fire, move that darn system where it belongs!
The main purpose for closing a crawl space is to control moisture and keep the crawl space dry. It has little to do with energy savings especially if the HVAC is in the attic. In cold climates, there is actually an energy penalty for heating your crawl space. I would not blindly say this is the answer to your problem.
If you feel a breeze in the lower 3 feet of your home, closing the crawl space will not likely solve your problem. If air is coming in at the bottom of your home it is a result of exfiltration at the top of your home. You need to start by air sealing at your attic/ceiling. After air sealing at the attic you can move to the crawl and air seal down there. A blower door can measure your progress, help identify exactly where the air leaks are and is necessary to calculate your ACH and if ventilation is required. If you call an insulation contractor he will sell you insulation. Hire an experienced auditor and get a house as a system diagnosis that will look at the big picture. If you have combustion appliances - be sure they perform worst case testing in the CAZ zones.
There is no way i'm going to pay to have an HVAC moved to the crawl. It makes sense to me now that it should probably be there, but that process sounds extremely expensive and outside of my budget. The issue with sealing my attic is that there is very little room to work with up there....it being a cape leaves a small attic directly overhead upstairs and small dormer storage areas on each side of the roof.
anyway, the HVAC unit is on the left side there outside of the room. There are many different nooks and crannies to try and completely seal up there....but i guess it is something that could be done. Other than moving the HVAC, you're saying hit the upstairs first? Right now, it looks as if the roofline is insulated with batt insulation in the dormer storage areas, but above the rooms upstairs the ceiling is insulated....the roof itself there has exposed wood (what looks like decking boards to be honest). The orange in the image is my insulations...some areas it is the OLD stuff while other areas have been updated. some areas are lacking all together.
I know many things in my house are done oddly, this is becuse the house was built by the one and only owner back in 1950...some contractors bought it before me and did some renovations before selling it. Overall i feel the house has some issues but as a whole, the house is solid as a rock.
"The main purpose for closing a crawl space is to control moisture and keep the crawl space dry. It has little to do with energy savings ..."
Sorry Danny this incorrect. We have been closing and insulating crawl spaces in the Carolina Piedmont (not too far from Richmond VA where this project is located) for over two decades, both in new and retrofit construction, and the energy effects are dramatic. Stack or chimney effect drafting requires both an entry and an exit path. This house has plenty of both, which has resulted in suboptimal comfort conditions and excessive energy use. Closing both would be ideal but in this older Cape Cod with its complex attic condition the crawl space is the low-hanging fruit. The floor deck could be sealed from below with spray foam but perimeter insulation would be simpler, less expensive and would allow continued easy access easy access to plumbing and wiring.
".... especially if the HVAC is in the attic."
As has been repeated countless times repeated on this forum, the attic space is no place for HVAC equipment unless it is sealed and insulated. As I mentioned above this would be difficult or impossible to achieve in the cramped attic of a typical Cape Cod. I know this from hard experience. Removing the HVAC equipment and ductwork will make the task (somewhat) easier.
"In cold climates, there is actually an energy penalty for heating your crawl space."
This WOULD be true - if we didn't insulate first. Further, perimeter insulation of the crawl allows the home to take advantage of the thermal mass of the ground below it, which in Richmond will be at about 55° summer and winter. Win/win/win.
Brian I understand your budget does not allow moving the HVAC at this point. Go ahead with your original plan, it's a good one and you will see a huge improvement. By the way I very much doubt you will need to blow conditioned air to the crawl space, it will continue to be very air-permeable to the interior and it should stabilize at the same humidity as the home interior. Just monitor for a couple of years, you can always retrofit if needed.
James - Thanks for the response...i appreciate your breaking it down for me. As for the fan/blower in the crawl, couldnt there be a negative internal house pressure issue that may pull up moisture from the ground in the crawl? i do have a sump pump which only turns on during heavy rain, but i've never seen any mold or standing water issues in the crawl.
The issue i have after hearing everyones comments is making the move to do something when i have SOOOO many ideas coming at me. They all sound like they would at least do something....the attic would prevent a heavy chimney effect, but wouldnt address the issue with downstairs being so cold and drafty.....sealing/conditioning the crawl would likely eliminate the downstairs drafts, but the overall negative internal pressure will try to pull the air from elsewhere and WHAT IF conditioning the crawl doesnt solve the problem....at this point i'm just stuck on what to do.
How bout this: i have a limited budget. I dont want to spend more than 2,500 right now and have gotten quotes to complete the crawl as noted above within this budget. With this budget, what does everyone think i should do RIGHT NOW in order to remediate the issue at hand (VERY cold downstairs and drafty floors). Remember, my flooring under my hardwoods downstairs is the pesky gappy-plank and not sheets of plywood.
Brian,
I think you misunderstand basic air leakage issues in a house. You wrote that air sealing in "the attic would prevent a heavy chimney effect, but wouldn't address the issue with downstairs being so cold and drafty."
Actually, it would. If you reduce the volume of air leaving your house, you also reduce the volume of air entering your house. Air in = air out.
Good morning Brian,
Wow, I can see that you are a little reluctant to make a decision about where to put the money.
If you go to the link that Robert Riversong posted titled "How's The Weather" you will see a posting of my home. Let me know if my house looks anything like yours. These 50's all brick capes can be trickey buisness and I have had lots of experience with problem solving these guys.
Many of the original exterior trim details allow for air to infiltrate at the point at which they meet the brick, lots of air. The standard approach to effectively sealing this type of home does not always work.
The good news is, it can be done in a very cost effective way. Half of the battle is the one that you are having now, Making the right decisions. Don't rush. You are learning your house now, read it like a good book, relax and enjoy it.If you get a chance to include a photo that would be helpful.
I would recommend putting the front part of your budget into sealing the obvious infiltration area's before the blower test. Most of these area's can be identified without the up-front expence.
When as much of the infiltration has been sealed that you can find without the energy audit, I believe that you will still have funds available to have the energy audit done.
By working this way you will have learned more about your home before the audit is performed, and will therefore gain more understanding from the audit.
I have photo's that I can share or Email to you that will demonstrate sealing techniques that I've used on similar homes with great success.
Thats my take at this point.
Martin - I seem to be more focused on my original plan i think of conditioning the crawl and adding a blower fan because i feel this is the only true way to get the warm air near the floor. With only ceiling registers, i worry that warm air will just short circuit to all the ceiling returns...thus my hope to add a fan/blower in the crawl pulling air from the interior assisting in circulating air beneath the home. I understand the issue with elimnating the chimney effect from the top, but feel the age of my house make it nearly infeasible from a (current) economic standpoint to seal up all the leaks.
I misstated in that i think it could eliminate downstairs drafts but not fully fix the temperature downstairs. I understand ventilation - Qin=Qout....i do worry that conditioning a crawl will likely pull air from somewhere else, HOWEVER, i think there is a chance that eliminating the primary source could reduce the overall inflow of air (it may at the end of the day make the pressure more negative, but that would reduce the inflow of air).
Roy - That looks similar. Complete brick top to bottom. When you speak of trim detail, are you talking about where the roof line meets the brick? other than that, i dont see many other points where air could enter other than the crawl venting and an oddly placed elongated window in the crawlspace.
That's right Brian,
On the gable ends, a frieze board is probably fastened against the brick. this detail is rarely sealed on a brick home the age of yours. lots of air moves through these locations. Also at all locations that have gutters there are the facia, soffit and frieze wood trim details that allow air infiltration. That frieze board just below the soffit is the big one. This means that there is opportunity for steady infiltration/exfiltration arount the entire house where the wood trim meets the brick. Take a good look and think about it.
I think an energy audit is his starting point. He should be looking for someone BPI certified too. I don't like the idea using salesmen to solve your problem. Salesmen look at issues of using their products and services to help you. In reality it may not help you and it may harm you. I also think it is not fair to call someone out if you are not really planning on using his services. The salesmen is working for his paycheck. The auditor is working for you.
Brian you need to understand the stack effect and thermal dynamics. Heat rises and hot goes to cold. Any air exiting mean new air is coming on from somewhere else. With the stack effect the heat is rising to the upper part of your house. Hot want to go to cold. It is warmest at the upper level it is seeking cold. The heated air is leaking out of all the small, medium and large openings. Combined a lot of air is leaking out.
All the air that leaked out has to come from somewhere. Since the hot air is rising it is pulling up cold air foam the bottom. Not so much the middle but the bottom. If you only seal the bottom you will lessen some of the air flow but it will start pulling more from the middle.
If the top level is minimally insulated and has a lot of air leaks the home will remain an energy hog and uncomfortable.
So what do you do... you work on the top and the bottom.
What is an audit going to do for you. It will get a professional to come out an evaluate your home. He will identify issues related to your house. He will tell you the order to do things and what is the most cost effective.
It sounds like you do not have any mechanicals in your crawl space. Without duct work and a furnace to work around may mean that you want to seal and insulate you floor instead insulating the crawlspace. An auditor will help decisions like this.
Step 1- Do what you are doing now. Learn as much about your home as you can before spending your money.
Step 2- Fix as many obvious problems as you can while still learning more about your home, without spending a lot of money.
Step 3- If you still have concerns or problems after steps 1 & 2 employ an energy audit service for guidance. The work that you've already acomplished will not have been wasted, you'll also understand the energy audit much better at this point. Possibly save some money as well.
DIY air leak testing, turn on all fans you have that exit the house. Use the back of your hand to explore all the case and base molding in your home. Get a low cost laser point IR temp gun. With mine I can even see the temp change at studs. There is a wealth of info online to do with weatherization. It is a big gov area of activity of late.
Take the trim off a door and or window. You may be shocked to find a hurricane blowing thru.
I'm liking how Roy is thinking right now. Robert - I do know Thermodynamics. I took it in college and also understand stack effect and ventilation in general (I have performed ventilation surveys in underground coal mines). What I do not know is how exactly houses are made. I feel there are thousands of methods used over the years and everytime i think i know what's going on, i find out it may not be the case. Could this mean i need the audit? Sure. Does completing the crawl now then doing an audit if it still doesnt completely solve the problem work? In A way I think so in that i at least take away one issue for the auditor to ignore.
I've gone ahead and attached a few thermal images i took from the outside of the home and a couple on the inside around some problem areas. I can see where the heat is leaving on the outside (upstairs roof vent and windows)...in addition you can see where the cold air is coming from on the inside.
As I see it, i understand how things work. I study them and actually find great pleasure in DIY work. My issue is that i've actually never built a house and really have no idea
Brian, A home is a series of layers no matter who or how it is built. Air leaks are at every single junction of materials.
So;
-Foundation to sill, spray foam or a compatible caulk, sprayfoam unfortunately works the best and is the easiest.
-Sill to rim joist, same sprayfoam or caulk
-rim joist to subfloor, same
-subfloor to wall sill plate, caulk
-top plates to whatever is next, caulk or sprayfoam, depends on the gap and what structure
-All penetrations, seal off. Pipes can be sealed with plumbing roof flange boots by cutting them in.
-Chimneys and other chases, metal flashing, fire caulk, rock wool
OK... I am repeating a very good list that is on this site somewhere. Somebody post the link.
Brian, looking at your last pic. Just look at the heat coming out of your attic vent!!! You are paying for that with cold floors and green dollars.
Just start at it Brian, you are way ahead of many of us having access to a FLIR camera. Look for air leaks, move insulation and trim out of your way. Small gaps caulk, wider gaps may need a material caulked in, and near chimneys you need to switch to fire resistant techniques like metal flashing and heat appropriate silicones and fire caulkings..
Brian, I think part of your dilemma is picturing the air movement as a zero sum game. It is not. Air out is not a fixed volume that must be replaced from elsewhere. Go ahead and seal the crawl space, the air flow through your house from bottom to top will be reduced and it will be reduced most emphatically at the floor plate where the symptoms of your problem are most severe. Increase the resistance of the system by closing the bottom end and air out through the attic will reduce proportionately, just as closing the air vent on a gasoline can will reduce the flow of gas out the nozzle. Any work you are subsequently able to do in the attic will further improve the situation, but start at the bottom, as you planned. Good building always starts at the foundation! If you email me at james at belladomus dot com we can set up a time to chat further on the phone if you like.
Brian, as you work on sealing the craw space, the info. that I posted on #9 will be relevant. I think you will get what I'm saying as you get into it. The photo's of the interior kitchen area confirm the possibility of joist pocket infiltration. Good luck
James, if you are in NC then I am sure you are aware of Advanced Energy in Raleigh - they are the closed crawl space experts and have done more research than any other organization that I know of.
I think they would disagree with you on the main purpose of a closed crawl. You may find this report interesting:
http://www.advancedenergy.org/buildings/knowledge_library/crawl_spaces/pdfs/NCEMBT%20Report.pdf
I do understand the benefits of a closed crawl and in certain conditions it can and will save energy if done properly. Other times it controls moisture and prevents the floor system of the house from rotting apart but there is often an energy penalty associated with this especially in winter and in cold climates. My point was not that we should not consider a closed crawl as a possible solution but it is too often overprescribed by salesman and often not necessary. You cannot blindly say for sure to close every crawl and magically solve every problem. ALL home performance/weatherization organizations and training facilities recommend to ALWAYS start at the top with air sealing. If you have a leaky top, sealing the bottom only moves the neutral pressure plane and can potentially bring in more air through the walls, doors and around the windows. I think the best advice to Brain is to hire an experienced BPI (or other professional) energy auditor that will look at his house as a system and make reccomendations based on their observations.
I also understand that the attic is not the ideal place for a HVAC unit and ductwork but the fact is there are millions of homes that are built this way. Giving the advice of relocating the unit to the crawl and closing the crawl by insulating the exterior walls cannot ever be justified by an ROI or a simple payback which most people will consider an important part of the equation.
Danny, from your linked study:
"The Baton Rouge study results provide strong support for the application of closed crawl space systems as a humidity control method for crawl spaces under homes in the hot-humid U.S. climate zone, and the results provide even stronger support for the use of wall-insulated closed crawl spaces, which provide energy savings in addition to humidity control."
Agreed, the parallel study in Flagstaff did not provide the same support for sealed crawl space. I suggest the Richmond climate location has more in common with Baton Rouge than Flagstaff.
In addition to all the advice here, Brian, GBA has a detail page on sealing a crawlspace that can show you how to do it.
James - I believe you are missing my point - I'm not trying to suggest that closed crawls do not provide energy savings and that we should not do them. I am a believer in closed crawls and install many of them. I was merely suggesting that closed crawls are primarily for moisture control and the fact that sometimes they do happen to save energy is an added benefit - that is not always the case. They do perform better in warm/humid climates. Even though in some cases the study supports overall energy savings, there is in fact an energy penalty during the winter in both cases if you study all of the graphs carefully. I think this fact is often overlooked and ignored.
You may be correct that Richmond may have more in common with Baton Rouge than Flagstaff for the majority of the year. But here in Brian's case, he is referring to a winter problem. During the winter, I would argue that Richmond is closer to Flagstaff than Baton Rouge perhaps if you compare HDD for the months of December and January so kind of depends on how you look at it. I am not trying to argue about small details here and would like to stay on topic of Brian's house, just pointing out that everything is not always black and white.
I do think Brian is on the right track if he does decide to close his crawl to install an exhaust fan. You recommendation to passively condition the crawl is a code violation. In a closed crawl you must have ventilation either by a supply only, exhaust only or a balanced system. I always recommend exhaust only systems for existing crawls for several reasons but in Brian's case will also help reverse the stack effect.
Danny, I guess we'll have to agree to differ. Controlling crawl space moisture is not the main purpose of a closed crawl space, it is a necessary prerequisite to that work which needs to be done by proper exterior and interior grading, waterproofing and draining before any sealing and insulation. The main purpose of closing and insulating is to improve energy performance and indoor air quality, and has been the case since the practice began over two decades ago.
You are correct that failing to condition or actively ventilate the crawl is a code violation in NC, I do not know the VA code position. We were associated with many closed crawl installations where this was not done before this became a code requirement here and I know of no cases where there were adverse consequences. Brian and his installer should obviously comply with local requirements. I would advise against active ventilation to the exterior as this will increase air flow through what is already an overly leaky house. The system that Brian proposed in his initial post is preferable.
Brian,
Keep it simple while you learn about your home. It's really not as complicated as some make it sound. Let me know if you would like to see photo's .
James - I agree we should agree to disagree - a minor point that does not really matter in the big picture I guess. I feel lke we have somewhat hijacked this thread and gotten a little off track. If you have any research on this outside of Advanced Energy I would like to see it.
Here is a decent report referencing some of the older studies:
http://www.advancedenergy.org/buildings/knowledge_library/crawl_spaces/pdfs/Moisture%20Solution%20Becomes%20Efficiency%20Bonanza.pdf
Enjoyed the discussion.
Brian - please keep us in the loop on what you decide and what type of results you experience.
Hey Danny, I've enjoyed the discussion too but I don't think we should be apologizing for going off track. GBA is overwhelming dominated by cold-climate new-build threads and this is the first in quite a while that has addressed an extremely common situation with older homes in the mixed-humid southeast, climate zone 4A. I've lived and practiced in this zone since 1991 and have been fortunate enough in that time to work with some excellent contractors and with a consulting firm which has been a pioneer of engineered environmental systems based on sound scientific principles since the the 1980's. We have worked together on energy and IAQ upgrades to homes dating from every decade in the twentieth century since the 1920's. However, North Carolina is still dogged by diehards who are deeply suspicious of anything but a musty, humid mold-ridden crawl space because that's the way it has always been done. We see the results of this in the present code: actively ventilating a closed crawl space is like calling for help but not too loudly so that we don't disturb anybody. Or like spending a small fortune on foaming a roof deck and then adding a power vent through the enclosure 'just in case' (I've seen it done).
Danny - I see what you mean with using more energy during some of those winter months with a conditioned crawl. In my situation, i dont picture this happening. At the moment, i feel the heat pump runs excessively due to the overall inflow of air leaks in the house (most of which feel to come from the floor). Correcting this primary leak could possibly reduce usage. Also, usage bothers me, but to improve the overall comfort of the downstairs is my primary concern. Make my wife happy and i'll be happy to continue paying what i am now.
James - I agree with your statement that air in doesnt always mean air out...i was trying to get this point across earlier. What i'm most concerned with is how roy said there is a chance air could be leaking inbetween wall joists all the way up from the attic line. If that is occuring, then i dont feel conditioning the crawl would necessarily solve the problem (that makes sense, right?). Overall, i'm still definitely leaning towards completing the crawl, im just still finalizing putting the pieces together.
Roy - If you have some pics, that would be great. I'd like to know what to look for regarding those possible wall joist leaks...if i can see the concerns you had then maybe i can prove, or disprove, the air is coming from other locations. I'd get you some of my own, but all i can do right now is provide you with the FLIR images above. If you'd like to send them to my email, it is [email protected].
Thanks to all for commenting. This is great stuff. Definitely helping.
Brian,
You wrote, "I agree with your statement that air in doesn't always mean air out."
But it does! The volumes have to match! Otherwise, you would be progressively pressurizing (or depressurizing) your house until (in the memorable phrase of Michael Blasnik) the house either explodes or implodes.
Martin - It does once steady state is reached...but if the system is changed to reduce flow in, then it's not necessarily going to mean Qin will be the same as Qin before the change. I feel if i take away that very large inflow of air, the heat pump wont be able to make up for that large flow and could actually use more power to produce less flow...sorta like puting your hand over a vacuum (probably not a good thing, but at this point i just want to be comfortable). Once steady state is reached in the new system, Qout should equal Qin.
HOWEVER, if we do want to get technical, Qout will not ALWAYS match Qin if air qualities change significantly within the system. For a house this is negligible...for a large mine 3000 feet under the ground, not always negligible.
Brian,
When I get back to my home office I'll post some pics, or email you some. May be around 6 pm.
Brian
You stated that you have plank subflooring. You have a lot of air exchange between the crawlspace and that house. If you put a poly vapor barrier on the crawlspace floor it will still be an uninsulated floor. At least you wont have the moisture seeping up. The other thing you have talked about is spray foaming the crawl space wall and seaing the vents. Is the crawl space accessible from outside or from inside the house. If access is from outside then you will need to air seal and insulate the access. In the end crawlspace will still leak.
Although this will improve the crawlspace condition the question is how will it affect the rest of the house. You have not addressed the swiss cheese layer between the crawl space and the house. If the top of your house is still leaky and will the stack affect you still be pulling in a lot of cold air from the basement.
Before doing anything you should define your air barrier and thermal barrier location. Then prioritize the steps to get to a finished project. Why closeup the crawlspace if you are later going to find out that its better to make the thermal/air barrier at the bottom of the floor level.
I dont know the age of your house but beware of knob and tube wiring prior to do any insualting.
Brian, your intellect might be getting in your way. Martin is dead on 99.9999% of the time.
Your home is a standard leaky hardly insulated home. Start sealing it up. You could heat that cold floor many ways. In the early 90's I added staple up pex radiant heat to a floor like yours that was cold as hell. Below the pex was reflective faced insulation as per recommendations. Now that house is the most comfy home any of my clients own. You could tap a hot water heater to supply it if you wanted save. Do it yourself for $5,000 or less and about two weeks of spare time.
In any event, get to the work, you are ready to go. Have caulk gun will caulk cowboy. Time to ride.... saddle up.... onward Ho.
Wow! That's a pretty high rating you've assigned to Martin AJ. How did you arrive at that percentage?
Roy, a year at this site and I agree with just about if not all that Martin posts. More than that he is never ever provoked. Calm, cool and collected. We are lucky. As to the other dozen bloggers, I often think their blogs fully miss key points. Check my posts in the blogs.
I know what happened of late has upset you. My condolences Roy. I have clearly stated my thoughts. We need to be civil. This site is privately owned. We are guests. We all are free to leave if this site is not working for us. The site fully has the right to maintain civil discourse however it chooses. All we can and should do is politely participate or pass and find a new forum.
AJ, Thank you for your kind and thoughtful responce. You are a true gentleman and should be well rewarded for the thought provoking insertions that you so readily offer to this privately owned site. Am I to understand that because you say so, is the reason and justification for giving such a high dead on rating to Martin as green building advise to Brian. Even after telling Brian that his intellect is getting in his way? We do need to be civil AJ, and I believe that both you and Martin know very well the intent with which you make these kinds of statements. Statements such as these bother me AJ and I am asking that you kindly refrain from this type of intimidation in the future . I pay for the use of this privately owned site and post with my full real name. I would even be happy to share my resume and credentials with anyone managing this site that might be interested. In addition to being sweet, kind and nice we must also be fair to each other.
Hello All - I'm back with some updates.
I decided to get the crawl space conditionining process done some in early February. The folks that completed the project did a great job and I feel overall it went well. The floors themselves werent as cold after completing the work...but...their were still the same, noticeable air leaks around the base boards within the interior of the home. This, obviously, was very frustrating to me. With that being said, I did climb up into the attic and move a little of the insulation in an attempt to cover some areas that looked to be missed. While doing this, I crawled to the edge of the house were the brick met the middle of the a-frame, and could see a potential issue. I could look down and see about a 1 inch space between the exterior brick and what looked like plywood....basically, it looked like there was a space for air to move between the wood of the home and the brick. From what I ended up reading, I feel this construction process may have been done purposefully in order to prevent condensation build up. Is that true?
Anyway - Roy, what do you think i should do now? I know we had very similar situations and I was just wondering what you think the next step should be. Once again, their WAS wall insulation, but I feel at this point it may be too old to be effective. Am I going to need to drill holes in the wall to reinsert insulation or is their another step I should take in order to target the air leaks.
Thanks for the help, again
brian.
Brian,
In a home with brick veneer, the air gap between the brick veneer and the wall sheathing (plywood in your case) is normal and proper. If your house was constructed properly, the exterior face of your plywood wall sheathing should be protected by a WRB like asphalt felt or housewrap.
To be sure that your home's air barrier isn't interrupted at the top of the wall, you should determine the most airtight layer of your wall -- usually your exterior sheathing (plywood) or your gypsum wallboard -- and you should be sure that this later is continuous with your ceiling air barrier (usually the drywall). If there is a gap at the perimeter of your attic, this needs to be corrected.