How to approach renovating the exterior of a house?
New homeowner here looking to improve house energy efficiency and durability.
The house (picture attached) was built in 1973. I’ve done some interior renovations since moving in and replaced the old R-7 fiberglass wall insulation with R-15 Rockwool on the first floor as I was opening up the walls. I also removed the old insulation in the attic and replaced it with R-30 Rockwool and added a layer of plywood on top so I could actually use it for storage.
Next year, I’m looking to do exterior work. The roof needs to be replaced down to the roof deck (planning on adding solar) and the siding is asbestos. On one hand I’ve been told to just wrap it, on the other I wanted to add a continous layer of rigid foam, possibly the Zip System 2 1/2″ R-Sheathing, but without removing the existing layers I don’t see how I’d have the “room” to add that much more thickness. Then I was considering putting hardiplank on top. The increased thickness makes me want to extend my roof overhang as much as possible but I don’t know what is possible without needing a major rework of the roof trusses and at what point I’m wasting money.
Lastly I was trying to figure out what I could do with my currently ventilated attic (has an air handler in it). Would it be too expensive to make it a conditioned space?
Sorry this post is all over the place. The problem is it feels like all of these decisions are connected so if I ask them individually it won’t be a good, holistic solution. I’ve been doing my best to learn about all the pieces, I just lack the expertise to know what’s the “right” or “best” way to do things for my situation. Also, shit the windows are all single pane and need to be replaced!
Would be great to get some guidance on how I should tackle this. Can it be broken up into separate projects without significantly raising the cost? If so what order would you tackle it in?
Also I’m in climate zone 5a and half way done moving from baseboard heating and no AC to heat pumps (first floor done) but holy crap my utility bill was still $843 last month! I live in a VHCOL area so I almost certainly can’t afford to do everything at once unless my goal should be saving up long enough so I can?
Thanks a ton for listening to my rant, I appreciate any insight you might have, also happy new year!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Send a piece of the siding off for asbestos testing. If it's from 1973 it's unlikely to be asbestos but it's possible.
If you're redoing the roof I'd increase the overhangs on the gable ends, it's always a good idea to keep weather off of the side of the house.
The hard part about adding exterior insulation is making the doors and windows work. Are you keeping them? If so, you may want to remove them, do the insulation and then reinstall further out.
Do you still use the chimney in the back? If you don't need it residing will be easier with it gone.
It's asbestos according to the building plans I got from city hall, but I'll send a piece out for testing, good idea. Remediation would be quite expensive where I live, I could consider tackling it myself (allowed in my state)...
How do I know how much I can increase the gable overhang by? I'm not particularly concerned with the "aesthetic" and am fine with whatever makes most sense.
All the windows need to be replaced, I've actually replaced two on the first floor already since I had the walls open. The front door I can replace. The two rear sliding doors I'm hesitant because they're good quality and I don't want to throw away money.
The chimney is still used for the furnace, which I want to get rid of. Either way the plan is to have a gas tankless for hot water but I don't need a full chimney for that.
Also worth noting that while I did some interior work the exterior I plan on contracting out.
Thanks so much for all your input. I don't think I can reply to those comments, maybe a max nested number... I was curious about this part
"If you're adding exterior insulation you can use the thickness of the insulation as space for the 2x4's that cantilever and support the extension so there is minimal modification of the existing framing needed."
Could you help me understand what you mean by the exterior insulation (I'm guessing the polyiso layer on the roof) giving space for the 2x4s? My current guess is, assuming the polyiso is 2" thick then in place of that, at the roof line, you'd sister a 2x4 extension?
Also is there a downside to the diagonal skip sheathing if I'm going the metal standing seam route? I'm assuming it's a budget minded move?
If you look at the picture, what Reisinger did was to nail 2x4's on the flat to the existing sheathing perpendicular and extending over the gable to create the overhang. That raises the surface of the roof by the thickness of the 2x4, or 1.5". If you're already planning on adding at least 1.5" of exterior insulation that's not a problem, you just skip the insulation where the 2x4's are.
if you weren't planning on insulating, and just keeping the roof height the same, the supports would have to go under the existing sheathing, which means reframing part of the roof to get everything to fit.
It looks like he's doing the same thing at the eave to extend the overhang there too.
Since you say the roof needs to be replaced anyway, I'd start there. Extending the overhangs a few inches shouldn't be a problem. With the air handler in the attic, what looks like limited space for insulation at the eaves, and the difficulty of air-sealing those top plates, moving the insulation to the roof line might be a good strategy. You could have the roofers add a few inches of foam (R-20+). Inside, spray foam to seal the perimeter top plates and add batts between the truss top chords and on the gable walls (hopefully you can make those R-30 batts work).
The windows would be my next focus, but it makes sense to replace them in conjunction with the wall improvements. If contracting the work out, it will cost less if you wait until you can afford to have the entire exterior redone. The solar would be the last thing on my list.
Ok I'll focus on the roof next year, thanks!
So if I understand correctly, outside have continuous rigid foam board and on the inside spray closed foam. What's the benefit of going with batts instead of just filling those spaces with the closed foam? Cost I'm thinking?
When you say "entire exterior" done to save money does that include the roof or just the siding windows and doors?
Interesting that solar is last on your list, why is that? ROI is longest maybe?
My suggested order of priority is roof first since it sounds like it needs replacing very soon anyway. Then windows and walls together (but can be separate from the roof work) because replacing the single-pane windows and reducing drafts will improve the comfort of your home. Solar will cut your power bill but won't improve comfort.
The main reason for the spray foam would be to air-seal from the wall top plates to the roof sheathing at the difficult-to-reach areas at the edges of the roof. Closed-cell foam would also provide high R-value per inch where it looks like there is only be a few inches of height. (But if I'm wrong about that and there is more height there, then keeping the insulation at the attic floor might be a better choice.)
With enough rigid foam on top of the roof sheathing, I think it's better to use a vapor-open insulation underneath so any minor amount of water that leaks through to the roof sheathing can dry to the interior. How much rigid foam is needed depends on how cold it gets there. Can you give a location? The other reason is that you already have new batts that you could probably move from the floor to the roof, even if they are thicker than the truss top chords are deep. You might have to add some depth by, for example, fastening 2x2s to the bottom of 2x6 truss chords to get a 7" depth to match the R-30 batt thickness.
If you prefer the look of minimal overhangs, you can just nail a couple pieces of 2x material to the gable end rafters and eaves subfascia (cut to match the roof slope). Wider overhangs will of course better protect the windows and walls.
I would start with the roof and you should see some of the biggest bang-for-your-buck in terms of energy efficiency and reduced heating/cooling. Most air leaks happen at either the lowest or highest points in the home.
Take off the old roof, put down a peel-and-stick WRB, then add exterior insulation (try to find some reclaimed commercial roofing polyiso sheets). Exterior insulation would be easier with no chimney if you plan on getting rid of it anyways. See Matt Risinger’s personal home and how he did after-the-fact applied overhangs. That might be a good option for you so you don’t have to mess with your existing trusses. He also used exterior insulation at the same time. Or you can sister new rafter tails to the current rafter tails.
Ok great point. Just focus on the roof for now, especially if that will be the best return on my money. I also think getting the joists in the basement insulated would be big. I can feel the cold at my feet when I stand at an exterior wall on the first floor!
When you say add WRB, should I be removing the old roof deck and replacing it first with plywood or something similar, or do I work on top of the existing 50 year old roof deck (is weight a concern)?
I was looking at polyiso for sure, how would I go about finding reclaimed commercial materials? Also, after the insulation is put down, does another layer of plywood need to be added for the actual roofing to be nailed down to?
For the exterior insulation and chimney point is that for the roof or the siding to make it easier? I do have two chimneys one is the boiler and the other is an active direct vent fireplace.
I'll checkout Risinger's stuff, thanks.
Also, do you happen to have an opinion on the roofing I should be considering? Cement Singles? Metal? Something else? On one hand this is my forever home but on the other I don't want to go for something more expensive if there's not going to be a tangible benefit in my lifetime...
I wouldn't remove the roof decking unless it's rotted. The peel-and-stick WRB will seal over any gaps and make it airtight. Do you have 2x material as your roof deck? Are they butted up tight against each other or is it skip sheathing with a lot of gaps?
Reclaimed polyiso: start googling, looking at Craigslist, or contacting commercial roofing companies to see if they have excess or if they know who buys/disposes of their reclaimed stuff.
You can do all of this without removing the chimneys, so don't worry too much if you need to keep them. Even if just for aesthetics.
Standing seam metal roofs are perfect for solar installation because they make clips to install the PV panels that don't require any penetrations through the roof (lookup S-5 brand roof clamps). So you will have no exposed fasteners and greatly reduce the chance of any water leaks. Metal roofing also has the small benefit of not needing a full layer of sheathing on top of the foam. Other options like asphalt shingles would require a full layer of sheathing. You can still choose to do a full layer even if going with a metal roof if you want. But with metal roofing you could also get away with 2x4 or 1x4 furring strips instead. This gives you a nice rainscreen underneath the roofing, but above the foam. You still use perforated soffits and that ventilated space connects to the under roof rainscreen area and finally to a ridge vent cap at the top of the roof.
Attached are some screenshots from Risinger's videos.
Sorry I think I may have missed terminology. By roof deck I was referring to the layer of plywood fastened to the 2x4s that make up the roof structure. I can see a minor amount of water damage in one corner on those so maybe just replace those as needed but the whole thing isn't necessary?
Also standing seam is exactly what I wanted. Lots of people have been telling me it's overkill or too expensive but I yet to get any real quotes.
So it would be this?
- Plywood (keep if possible)
- WRB on top
- Polyiso
- .... Standing seam roof directly on that?
The third picture, where the gable is extended 16-18", is what I would recommend for your house. If you're adding exterior insulation you can use the thickness of the insulation as space for the 2x4's that cantilever and support the extension so there is minimal modification of the existing framing needed.
Standing seam needs something to screw into, but it doesn't have to be continuous sheathing. It could be pieces of 1x3 or 1x4 spaced every 16". This is called "skip sheathing."
Like DC said, you need some sort of material for the metal roof to fasten too above the polyiso. It can either be another full sheet of sheathing (plywood or OSB, doesn't matter) or it could be 1x3, 1x4, 2x4, etc. boards. Usually these boards are put at an angle (diagonal) across the roof because the standing seam vertical panels need horizontal bracing. You could also just put the furring strips horizontal but it encourages water (that is very unlikely to get under the roof) to pool up on top of each ledge created by the horizontal furring strips, so diagonal would be better although a little more complicated. Risinger has older roofing videos where he does this.
Deleted
Thanks for all the help here, I can't reply to the last comment you made so just wanted to ask here, are there pros and cons for doing the continuous vs skip sheathing in this application?
Going to give into his videos tho, thank again.
The furring strip method should end up being a little cheaper and requires less screws, and given that you will be trying to drill those screws through thick exterior insulation that could be a good reason to try that method. I would suggest getting a portable drill guide like the one Rockler makes to hit the studs through the insulation. The full sheathing method will result in a more durable roof that you can step all over without fear of denting the metal panels. It will have much less open area for the rainscreen though. I personally haven't done either method, but when I eventually build, I plan to go with the furring strip method.
Deleted
Before you spend any money write down your goals for this home and a budget.
Sadly, I think the current unwritten plan is deep energy retrofit the numbers are not going to add up because they never do. Doing the deep energy retrofit one step at a time will triple the cost.
It seems you have already spent a lot of time and effort into the house and not increased its market value. My guess is if you have your real estate agent have a look, they will struggle to find something nice to say and discourage similar work.
My guess is that you would be better off building what you really want this place will always fall short of your goals.
Why disturb the asbestos siding it is almost indestructible it holds paint well and is not a health risk as is.
Walta