Insulating an older house

[greg Forster]

I'm doing a total renovation on my
home and am running into a lot of questions I don't have good answers to, how to insulate being just one of them.
The house is an 1840s two story post and beam located in Piedmont NC.
The siding is nailed directly to
the studs- no exterior sheathing.
The interior side of the walls as well as the ceilings are sheathed in wide T&G boards- hand planed (scalloped cuts of a foreplane quite visible).
I plan to carefully remove the wall boards- do structural repairs, install
MEPs, sheetrock and then replace the
boards in most areas- either painting
or wallpaper .
One big question is how to insulate
and providing an effective vapor barrier. My concern is during the Summer with AC - moist exterior
air moving into the conditioned interior.

I'm open to any and all "Brain-storming" ideas/thoughts

[Tom M King]

Look on my website at an 1828 house I insulated. On this one, the interior wall was much more preserved than the outside, and we wanted to disturb the interior walls as little as possible. We pulled all the siding off. Cleaned everything with bleach and water. Once it was dry, 6 mil poly was wrapped in and out of all the stud cavities.

The plastic wrapped all the studs, and covered all the interior walls. Once the plastic was up, we pulled all the wires that went through the walls. This house had never had a wire or pipe in it. Once we had everything that needed to go in the walls, we stapled a non-woven olefin agricultural fabric ( provided by the insulation company) to the outside of the studs. After using a hammer stapler to do this for a while, I ordered a full automatic stapler that would shoot three strips of T50s in a couple of seconds. The olefin fabric allowed the air back out from the insulation blower, and held it in place. After the insulation was in, we put a layer of Tyvek over it, and installed new, clear Cypress siding, that we had milled to match the original. The original siding had about weathered away to nothing, but the top boards under the soffit told us how to make the replacements.

After that fabric was up, the insulation came and blew some sort of finely chopped white fiberglass behind the fabric. I don't remember the name of it, but it was made in Germany. The house is nice and tight now.

There should be plenty of pictures on my insulation page to be able to understand the process.

I would seriously consider doing it this way, rather than risk damaging the t and g boards on the inside.

www.HistoricHousePreservation.com (http://www.HistoricHousePreservation.com)

I just checked, and it doesn't have a picture of the vapor barrier. If you don't understand what I said about it, I can probably find a picture somewhere. We held the poly in place with thin strips of wood stapled to the studs, next to the interior wall, with a small air stapler. I took the quick disconnect off the nailgun, so I could get it into tighter corners near the diagonal braces.

If you don't want those old t&g boards, let me know. Someone stole a bunch of them out of the attic of that house, which is actually three nice rooms, and we haven't found replacements.

We're probably not that far from you. If you'd like to come look at that house, PM me, I'll tell you where it is, and give you my contact info.

[Jim Becker]

If you are going to remove the interior wall boards, once you are done with wiring and plumbing renovations, consider having closed cell spray foam installed. It's not inexpensive, but it provides some significant benefits, including integral vapor barrier, high-high R-values and meaningful structural strength. And it can get into all those odd-shaped and sized places that are typical of older structures. You can also use open cell spray foam, but you lose the vapor barrier and structural benefits.

[Brian Elfert]

I'm with Jim on why not use spray foam? It is more expensive than fiberglass, but it may be no more expensive than all the special work required to insulate an older home. It typically provides a vapor barrier as well.

I just had an inch of spray foam installed in my attic due to lack of vapor barrier. I will have no idea how much it reduce my heating bill as I also installed new windows and doors and converted from electric to gas heat. The gas heat alone will cut my utility bill at least 50%.

[Pat Barry]

I just had an inch of spray foam installed in my attic due to lack of vapor barrier.
How / where did they spray? Over the insulation you already had or under the roof sheathing between the rafters?

[Brian Elfert]

How / where did they spray? Over the insulation you already had or under the roof sheathing between the rafters?

All of the existing insulation was removed first, a one inch layer of spray foam put on the floor of the attic, and then fiberglass blow-in insulation was added on top of that. Fiberglass is cheaper than a thicker layer of spray foam. Besides no vapor barrier the vents were plugged with insulation so the attic had no ventilation. The insulation company fixed the venting issues too. Total cost was close to $5,000.

[Pat Barry]

All of the existing insulation was removed first, a one inch layer of spray foam put on the floor of the attic, and then fiberglass blow-in insulation was added on top of that. Fiberglass is cheaper than a thicker layer of spray foam. Besides no vapor barrier the vents were plugged with insulation so the attic had no ventilation. The insulation company fixed the venting issues too. Total cost was close to $5,000.
OK = that makes sense. Thanks

[Tom M King]

If the house is on the Historic Registry, they don't like spray foam, or any such that bonds to the old parts of the house. Other than that, it would be my choice too.

[greg Forster]

Tom,

thanks for your information and a great web site, I've visited it several times; you're doing what I dreamed about doing for years. I was project supt. for a GC for 10 years converting old buildings(some as early as 1830s & 1840s)- mills, schools, a tobacco prizery,etc. into apartments, retail and commercial spaces.But, almost all masonry structures. (Now I do luxury apartments- mid-rise and podium projects; not as much fun, but pays better).

I have/am still considering the idea of removing the siding- I will be doing this on the one story rear kitchen wing- that siding is not original, (the part of the building was enlarged slightly and this siding is beveled/circular sawn though still nailed with cut nails;

the siding on the 2 story is original "heart-pine" lap siding ; its covered with vinyl siding now, but where I've removed some vinyl to investigate, it looks to be in very, very good condition- I think this siding always was kept painted; its 3/4" thick and not beveled- cut on a sash saw. I removed a little at the sill beam - very tough to do, I'm afraid I would destroy a large amount .

I think (right now anyways) I will have more success with removing the interior boards with minimal damage; I just have to come up with the right technique.

The entire issue of insulation, vapor barriers, etc gets more confusing the more I read about it- of course I'm probably 10 months+ before I get to this stage(doing all the work myself), so plenty of time to get even more confused.

[greg Forster]

Jim,

the closed cell foam is something i'm looking at; also thinking along the lines of a plastic mesh strip against the interior face of the siding- to provide an airflow between the siding and insulation. Not sure if this is
useful or not- just alot of opinons out there

[greg Forster]

Brian and Pat:

the closed cell insulation sounds interesting. I'm really concerned about a vapor barrier. Looking on some manufacturers' web site, they note the closedcell foam as a secondary vapor barrier- not sure what that means; is a primary vapor barrier, i.e. Tyvek, still required?

[Tom M King]

If you decide you aren't going to use any of the T&G interior boards, the owner of that 1828 house would probably want me to come remove them. I can work out a deal between you two for him buying them.

[Jim Becker]

Brian and Pat:

the closed cell insulation sounds interesting. I'm really concerned about a vapor barrier. Looking on some manufacturers' web site, they note the closedcell foam as a secondary vapor barrier- not sure what that means; is a primary vapor barrier, i.e. Tyvek, still required?

In a retro-fit situation, the closed cell foam will give you a great vapor barrier and since removing the outside siding isn't going to come into play here based on previous discussion, a wrap really isn't possible. One could, of course, go with open cell trimmed flush (or hand-cut unfaced fiberglas) and a poly vapor barrier on the inside, but that would have a lower R-value. One other thing...doing all the work from the inside makes a lot of sense on a project like this because modernization of electrical and plumbing often comes into play and that means opening up the walls to "do it right" anyway.