Planning phase of a new build. Seeking advice early, variety of questions
Markeyro
| Posted in General Questions on
tldr: would like some advice on questions below
Been lurking for a while on GBA. Recently subscribed to get all the good stuff as my wife and I embark on building a home in the next few years.
I’ve been thinking about this for a good 10 years+ and as things come more into being a reality I thought I’d take the shot at putting out some quesitons to this group for feedback. Certainly nothing new, but a few questions I’d love some input on related to wall assemblies, window placement in thick wall assemblies, and some pretty good house questions.
Some basic info and priorities:
– Live in climate zone 5A, Muncie IN, just north of Indianapolis
– Here’s the link to our ashrae data for this location (city close by):
– Lot is a strange 1.7acre right triangle with an unobstructed southern exposure; Open to West side; Angular side is to the NE w/ trees all the way along
– Will be on a well
– Will be forced main / pressured to county sewer line
– Electric available; Gas is not
– Will be on a well
– Will be forced main / pressured to county sewer line
– Electric available; Gas is not
Primary goals:
– NUMBER 1 Priority – Excellent Indoor Air Quality (wife has extreme allergy / respiratory issues)
– Aiming at a net zero electric home via solar
– Performance Targets: ACH50 of 1; R25/45/70 basement/wall/ceiling
– HEPA Merv 13 minim; ERV; Whole house dehu; Ductless MiniSplit setup
– 1600sf max footprint; 3200sf total w/ finished basement
– ICF Basement; 9-10ft; Main floor 10′ Ceilings;
– Master and 2nd BR on main floor ; 2 BR in basement
– Well planned and executed, clean MEP room in basement
– Budget; Want to generally keep it simple stupid mindset; Well executed simple design and flashing. Not an extravagant flashy build
– Nice outdoor covered porch space; Not some crazy outdoor kitchen, pintrest 100k backyard
Thoughts on the following issues/questions/plans???
– 1st floor wall assembly. I’ve been most enamored with a simple double stud wall assembly. Unsure on exterior finish yet. Rainscreen; Zip on the external walls; Dense pack cellulose in wall; Talk to me about smart vapor barriers on the inside framing (looking at intello plus); strapping to the inside to create a service cavity/surface for drywall. Would love some “real world” advice on the smart vapor membrane topic. Lots of interesting and varied opinions out there.
– Trussed roof system; Raised Heel; Room for loads of blown in cellulose; smart membrane to cover ceiling as well obviously.
– Window location in the thinck wall assembly? Pro Cons of “mid depth” windows or flanged “normal” install windows or full innies?? Complex flashing details, etc.
– Not really a building science questions but thoughts/advice on: “Build Now” versus Waiting for the “perfect time” (cough,cough) to build?
– Thoughts on preferable, easy/efficient to install, budget friendly exterior finishes?
I guess that’s a good place to start. I’ve read a ton of articles here on the site, but don’t hesitate to point me to those posts which you think might offer insight. There’s tons here and I’m certain I’ve missed a bunch.
Really appreciate the help, this is a pretty amazing community.
Thanks in advance!
Mark
Thanks in advance!
Mark
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Replies
I’d immediately ditch the ductless path and use ducted. Ductless can’t handle a well insulated and air sealed home with many bedrooms. They also can’t filter air whatsoever. A ducted system fits the requirements so much better and you’re already installing ductwork!
Thanks Paul that's good feedback to consider. I will have some ducting with the ERV and humidifier in addition to quite a few ceiling fans to do some air mixing. I've had such poor experiences in the past with dusty dirty hvac ducts, my thought was to try and minimize this. Also will be filtering with the ERV. Will reconsider this point though. Thanks!
Ductless heads, which you will have a lot of, get so filthy. They’re not for filtering.
If you want to filter your inside air go at least partially ducted with a proper filter. Remember the ERV only filters out outside particulates, but particulate is generated inside the house that the coarse ductless filters can't handle. Even worse ductless units end up filthy if used for AC, mine was as bad as this after 3 years ...
https://www.energyvanguard.com/blog/ductless-mini-splits-can-get-nasty-inside/
I say build now it will only get more expensive if you wait assuming the plan is to move in immediately.
Understand this is a custom home and it will cost 20-50% more per square foot then the production builders stuff.
Is the lot well drained? When you stand on it is it clear where the water will go? In that part of the country the only hills are where the road goes over the highway. LOL
When you pick your builder choose carefully you are married to this person for the next year. There will be good and bad days.
If you need to lower the cost cutting the square feet and window area are the only things that really work.
Is the lot dry enough for a full basement?
I have not seen a ductless mini with a factory MERV 13 filter the factory filters seem designed to stop stick and stones. Like Paul said look for a ducted mini and make a plan for the duct locations from the beginning. Often there is no plan and it is up the HVAC guy make it fit.
Practice saying NO to stupid. People will offer you the stupid option over and over again.
NO large areas of spray foam!
No skylights!
No ductwork in the attic!
No sloped ceiling!
No half story designs!
No bigger windows just for solar gain!
Walta
Thx Walta. Appreciate all your thoughts especially the last section of No's. Couldn't agree more. Will definitely rethink the hvac overall plan/approach. The lot is dead on flat and there are pretty significant ditches to the front and back angled side. We do have a pretty high water table around here and I am somewhat worried about this, but my plan/hope is to get a geotech analysis before starting and also only go down about 7 ft and build up around the house to provide some slope away from the foundation.
Build now is advice I've heard from others as well. Yeah, things aren't getting any cheaper. Sometimes hard to weigh and balance how much prep time and savings time to go for. Many thx for the feedback.
The poor man's geotech analysis:
Get an auger like this -- https://www.amazon.com/gp/product/B00002NCFZ
The handle is a piece of iron pipe, you can screw it off and extend it with 3/4" iron pipe and couplings. Unless your soil is really dense you can dig down ten feet or so pretty quickly. That will tell you two things. First whether there is bedrock or similar which would block you from digging. Second whether there is a high water table. Obviously the water table moves with the seasons so it's not foolproof. Soil that has been inundated has a different look, a soils expert would be able to look at the soil you bring up and tell if it's seasonally inundated; I don't know how to do that.
Thx man, I might give that a try. We started a perc test with this very tool and the soils scientist was working pretty hard up to just 24" or so. It's super clay soils around here. I have some good data on water tables and wells in the area, water tables varying between 10-25' below the surface. Could certainly be an issue. I'm moderately worried.
I've just gone though this twice: once with my garage/ADU builder and currently with another whole house gut renovation builder. I've done renovations and homes before, so I'm somewhat dangerously knowledgeable, certainly more than the average homeowner, but not even close to these experts on GBA.
Hire an architect. Get recommendations of who the locals use. Building inspectors can have good leads for this.
Speak with both about builders. The building inspector sees everybody's work and the architect works with all of the builders. Get to know your BI. Ask for his advice. You need him way more than he needs you.
Interview a bunch of GC's. They come in all shapes, sizes, quality and cost levels. Try to get ideas of prices from them. Go see their projects. Talk with their customers.
I found some of them not returning my calls, some arrogant, some too busy and some way too expensive. My garage GC was a jerk and the house GC is a good guy. Do your homework. You're getting temporarily married like Walta says, while handing them boatloads of money.
Expect delays. Subs have their own schedule and you're just one job. They mostly come and go when they want. You have no control over them.
Don't make any major changes during construction. Try to stick with the plan, but be prepared to make decisions on the fly after asking everyone for their advice.
Expect your project to take longer than you want and make sure there are no major impediments to your schedule. (another home sale, money availability etc.) You don't want to be the monkey wrench in the works.
Good luck. It's not for the faint of heart.
Thx for the advice nynick. Yup, that all tracks for sure. I've gotten my hands dirty with several projects but I'm no expert either. I'm ready for all the issues in scheduling, poor communication, issues with subs, and always more $$ than you want to spend. It'll be worse than I want it to be for sure. I've gotta buckle up.
Having lived in that part of the world it seems a little strange now but a hill goes over the interstate and a rock is something you must buy from far away.
As I recall the old farm houses all had very tall foundations that put the floor about 3 feet above grade. If every few years or so a big rain came and water filled the basement or crawlspace it was no big deal as it soaked in to the ground and drier out before long and the space was never finished.
Walta
+1 on ducts, you want this in a new build. With a basement this is easy as you can run all the ducting through the floor joists especially if you go with floor trusses.
Do a quick tally of what you would put into a wall service cavity. You'll find that not much, and even less with a basement as all the utilities can run through the joist.
For the couple of devices boxes in outside walls, use the gasketed flanged ones (sometimes called vapor tight). Much simpler and barely adds any cost.
For a double stud wall in zone 5 you will need a warm side vapor retarder. This vapor retarder can be anywhere up to 2/3 way through your wall but simplest is behind the drywall. The mid wall barriers are possible but more work and harder to densepack.
I was recently driving in the countryside and there was a very nice farm house with unpainted board and batten siding and a red tin roof. It looked fantastic, low cost siding and essentially no maintaince. Does need the right style of house to pull it off though.
Thanks for the feedback Akos.
Yeah the vapor retarder question is one of the more interesting pieces of the puzzle with the double stud wall. Certainly seems easiest/cost effective install to put it to the interior of the interior wall, then strapping (i'm thinking 2x3), then drywall. One big questions is how necessary is the vapor barrier in this situation. drywall and paint certainly aren't smart, but are decently vapor open so drying should be able to happen. I won't skimp on this especially in a new build, but it's tempting.
And yes, i'm sold on going ducted v ductless.
My suggestion is to try and find a builder that's comfortable with most of the building techniques and items on your list. That could help you greatly simplify your design choices. Your wall assembly may not sound complicated on the Green Building Advisor forum, but it's not "standard construction". (Double stud wall with rainscreen, Zip, dense pack cellulose, smart vapor retarders and interior strapping). Yikes. I can't imagine explaining that to a typical builder.
I'm finishing up an extremely simple detached garage build. The walls consist of 2x6 studs on 24" centers, fiberglass insulation and Zip on the outside. When I told my builder about the wall assembly, he said "What's Zip?" That moment put everything in perspective for me. I'm happy with the builder and the quality of his work. He had never used Zip though. I did all the taping, sealing and window/door sealing.
I live in a very small town rural area so energy efficient construction is not common. Maybe there are people that understand advanced building techniques in your area (hopefully there are). I'm going to venture a guess that most builders in your area have never built a wall assembly like you're describing.
Find a builder that uses some energy efficient building techniques and discuss what's realistic. I'd rather have a simplified wall assembly that's well executed than an advanced, complicated wall assembly (that may be more efficient on paper) but is poorly executed. Do you want the builder (and all of his subs) to "practice" learning some new techniques with your house?
My two cents and best of luck with your build.
Thx Bluegoose68.
Yeah, this is actually something that is somewhat discouraging. It's a bummer that there aren't more folks in the building community who are invested in and interested in doing this kind of building and exploring these ideas and technologies. I did a quick search for Indiana Building Science on the bazillion of facebook groups and came up with nothing. boooo. Anyways yeah challenges in teaming up with / finding the right builder.
Hey Markeyro
I am in Indy and have been lurking in the building science world for a good number of years and recently did a "shallow" energy retrofit to my own home. I may know a couple builders who may fit your criteria, but they may not go further than the donut counties. Steve Baczek is actually building somewhere in north Indiana now that i think of it. Not sure if I can post the builder names on the forum but we can exchange info somehow. Good luck and i would love to hear what you ultimately find out.
I'd say don't try to find the "perfect time" to build. That's like trying to time the stock market. It's just not going to happen. Build now, or assume it will cost more in the future. I don't think you can do much better than that in a practical sense.
I'd forget about net zero. Net zero needs net metering to work from a cost effectiveness standpoint, and that's going away in many/most areas. Battery systems are a can of worms and introduce new issues. I'd try to do what I call a "peak shave" system, which means size your solar system to operate 100%, or just a bit more, of your expected total load during the producing time for the solar panels. Basically if you expect around 3kw or load during the sunny part of the day, size your system for 3kw output. You can decide how much you want to build to try to size for peak load in the winter or summer only -- it will take a lot more solar panels to get the same kw output in the winter than it will in the summer. Peak shave works regardless of the utility metering plans you have available, and it's a much more cost effective way to go overall.
You can get MERV 16 filters now. I'd consider those and some activated carbon filters to get the best air filtration you can. Avoid any carpet, stick with wood floors, drywall, tile -- hard stuff that won't make dust.
I'd be suspicious of the vapor retarder being used as you describe in a double stud wall, where it sounds like the membrane will be responsible for supporting the densely packed cellulose in the outer part of the wall. I think you're looking at the potential for a lot of tears in the membrane there, especially at fastener locations. I'd use some kind of cheap backer to take the load, maybe 1.4" waferboard or thin OSB, with the membrane supported by that. That way the strain is off of the membrane so you should be safe from tears.
No problems with raised heel trusses, but assuming a vented roof, you don't need a vapor retarder on the ceiling since the ventilated roof will deal with any moisture that sneaks up there. Just seal up the ceiling drywall to be air tight and you should be fine.
Innie windows I think offer potential for stuff to buidup on the outer part of the sill and cause problems. I'd go with outies, or some type of pitched sill on the exterior so that stuff rolls off and goes outside.
Bill
Regarding wall assembly, our recent projects have involved double wall and we really like this approach because it is very practical. I’m also located at the top end CZ5 (Ontario). Our DW assembly preference is the following from exterior to interior
-Cladding of choice
-1x3 rainscreen system
-Zip sheathing PRIMARY AIR BARRIER
-2x8 structural wall w/dense pack fibreglass R30
-Intello+ VAPOUR CONTROL/SECONDARY AB
-2x4 service cavity wall w/ DP fibreglass R15
-Drywall
Our team has figured out how to develop this assembly efficiently however there are important sequencing steps to consider in order to avoid labour inefficiencies. Also, this does require our insulation sub to make a second trip to insulate the service cavity wall, fortunately for us, he is located within 30 minutes from most of projects otherwise we may consider installing batts in the SC.
We also start by framing all of our structural walls (exterior + any load bearing interior walls if any) and then install our roof system. This leaves us with a wide open box (like building a shed) we then detail openings for the few penetrations that have to go from interior to exterior ie. ventilation supply/exhaust consumidor line sets, wiring and hose bibs. After that, we are left with wide open walls that makes for a very quick DP process and installing Intello + (I’d steer clear of Certainteed Membrine) is very efficient as there no interior walls to work around.
Onec the primary exterior wall/roof systems are in place and detailed, framing the SC and interior partition walls is about as simple as it gets.
I have posted lots of videos on my Instagram page describing this process if you’re interested
https://www.instagram.com/sommerbrothers?igsh=MW9hMWQxbTNiNmdtNQ%3D%3D&utm_source=qr
Lastly, I would agree with others that have suggested the importance of vetting a build team. An experienced traditional builder that is reluctant to work with “different” systems/materials may be a challenging relationship. Finding a builder that shares some of your goals and is willing to learn would be ideal.