Hi Kevin and welcome.
If I were you, I would do both. Sealing the wall/floor joint would be the easiest but if that space is open then foam away. Be sure to use the foam that does not allow vapor infiltration (closed cell?) It's interesting that your house's stone construction actually has an air space. My house has plaster applied directly to the stone with no air space. Don
Stone house wall insulation
Moderators: oldhouse, TinaB, Don M, Schag
stone house pointing
Seriously HB, that was the best and most concise description of how a stone house wall works that I've heard. Now you've got me worried. I live in a 1790 Maryland stone farmhouse. Unfortunately, with the advent of cement the PO's did a little repointing in the 1930s. Oh, the humanity! If I knew how to attach a picture I would, but just imagine very ugly cement slapped into every joint on the largest most beautiful exterior wall of the house. We've talked to several experienced "old-house guys" and it is going to be prohibitively expensive ($100,000) to repoint the house so we plan to leave that for the end of our long restoration plan (like maybe after we're dead). I kind of figure that since it's been 70 years since they repointed (they signed and dated the pointing, so we know exactly when they did it) that it will be ok for a few more years. I'm curious about your opinion.
As for the original question on this posting, I can't imagine pulling off all the old plaster. It gives such character. We have one area where they did fur out the walls and it seems so "new" looking. My neighbor also has a stone house of this vintage. PO's did fur out their walls to insulate. It ruined the look of the rooms because the woodwork doesn't look right, especially around fireplaces. I did however see a local house where they successfully altered the woodwork to hide the furring, but as was said above--why worry about the 18 inch walls--the heat loss is from windows and the roof.
BTW if you need to hang anything on your very hard plaster walls you can buy special masonry wall picture hangers. They are white plastic and have a bunch of short little nails that go into the wall. They work very well--get them at Lowe's or HD.
As for the original question on this posting, I can't imagine pulling off all the old plaster. It gives such character. We have one area where they did fur out the walls and it seems so "new" looking. My neighbor also has a stone house of this vintage. PO's did fur out their walls to insulate. It ruined the look of the rooms because the woodwork doesn't look right, especially around fireplaces. I did however see a local house where they successfully altered the woodwork to hide the furring, but as was said above--why worry about the 18 inch walls--the heat loss is from windows and the roof.
BTW if you need to hang anything on your very hard plaster walls you can buy special masonry wall picture hangers. They are white plastic and have a bunch of short little nails that go into the wall. They work very well--get them at Lowe's or HD.
LZ, We have the same Portland cement dilemma. I am currently repointing my 18th c. Stone house in Virginia. I have decided to do it myself and it's a tremendous undertaking. I have experimented with various tools to remove the Portland that was buttered over the stone joints. I have determined that cold chisels of various sizes and a careful blow of the hammer are working great. I hope your current repointing was not packed into the joints but largely buttered. Portland cement in the joints of a masonry wall are a cancer to the structure. The Portland will invariably crack, allow moisture to infiltrate and damage interior surfaces. Just as bad is its result on the masonry itself. The PSI (pounds per square inch of pressure) necessary to crack 18th and 19th century stone and brick are far less and need lime based mortars that will move with the wall. In other words, when the wall goes through its natural seasonal movements, the mortar will not move with it because its harder than the surrounding brick or stone. The result it cracked stones and bricks. The purpose of your mortar is to stop wind driven moisture and nothing more. We could remove 100% of the mortar from our houses and there would be no structural degradation. When it rains the wall (and mortar) should absorb water like a sponge and then release it as quickly, when it stops raining. The Portland will eventually allow water in and hold it. Your Maryland stone is probably more substantial than my Shenandoah Valley limestone and I suspect you will have an easier time with your repointing. Good luck!
Currently living in 18th c. Virginia
LZ, if it's been that way for so long, I wouldn't rush it to the top of the list, but take a look around the wall that was repointed with cement to guage the amount of damage that may be occurring.
Look at the interior surfaces along that wall for white chalky staining and for Eflourescence. (shiny crystalline looking stufff on the wall.) Portland cement releases sulfurized salts which can deteriorate original lime based mortar/plaster. This can prevent lime based plaster patching from working.
If you see any significant cracks in the pointing, fill them with lime based mortar to keep moisture out of the wall.
You CAN repoint the place yourself, just be sure to use hand tools only (NO POWER TOOLS) so that you don't damage the stone and wind up with odd looking joints that are too wide. The object is not to perfectly remove every little speck of cement, just remove most of it for the wall to work properly again.
TO repoint, I would buy or rent scaffolding and start at the top. Remove a portion of the old pointing , let the area dry out for a few days and then repoint with lime based mortar, then move to the next section. IT's a long project for sure, but not impossible by any stretch of the imagination.
I would bet that even with the cost of the scaffolding and other tools thrown in, you won't top 10k in costs to repoint the place. (although it may take you a lot longer.)
Best of luck, and DON'T PANIC.
HB
Look at the interior surfaces along that wall for white chalky staining and for Eflourescence. (shiny crystalline looking stufff on the wall.) Portland cement releases sulfurized salts which can deteriorate original lime based mortar/plaster. This can prevent lime based plaster patching from working.
If you see any significant cracks in the pointing, fill them with lime based mortar to keep moisture out of the wall.
You CAN repoint the place yourself, just be sure to use hand tools only (NO POWER TOOLS) so that you don't damage the stone and wind up with odd looking joints that are too wide. The object is not to perfectly remove every little speck of cement, just remove most of it for the wall to work properly again.
TO repoint, I would buy or rent scaffolding and start at the top. Remove a portion of the old pointing , let the area dry out for a few days and then repoint with lime based mortar, then move to the next section. IT's a long project for sure, but not impossible by any stretch of the imagination.
I would bet that even with the cost of the scaffolding and other tools thrown in, you won't top 10k in costs to repoint the place. (although it may take you a lot longer.)
Best of luck, and DON'T PANIC.
HB
Similar Questions
Hi. I just joined this site, inspired in large part by the excellent posts on this thread. My apologies about how long this post is about to become, but I'd rather give too much background than too little.
My house presents a slight variation on this theme. I have a 1920 Dutch Colonial, with stone on the first floor and walk-out basement, siding on the second, and a pent roof in between. The siding is currently foam-backed aluminum, covering the original wood (which appears to be in decent shape). I had an energy audit with blower door test, which revealed substantial air infiltration -- more than could be explained by the leaky windows and attic. The air could be felt strongly through recessed lights in the first floor ceiling, leading the auditor to suspect the pent roof -- though he could not find conclusive proof. He thought there might be open joists to the pent roof, although later inspection during a soffit repair revealed sheathing covered by felt running all the way down to the stone. Interestingly, the auditor estimated the cavity in the stone wall at 3-4 inches deep. For my own part, I removed an outlet in the baseboard of my dining room and measured 9 inches before hitting stone!
My first attention has been to the attic and windows. In spite of much conflicting opinion, I went ahead and had the underside of the roof deck sprayed with foam. Whatever other issues that may raise (hopefully none) air infiltration and heat escape should not be among them. The old double hungs are in pretty good shape, with those on the north side equipped with metal weatherstripping running in channels routed in to the sashes. I've been rebuilding and adding weatherstripping as needed. All of the windows have storms, including some with very old, very heavy, and very attractive double track aluminums made by Burrowes. Unfortunately, most of the second floor storms were replaced with standard triple tracks in the 70's, and I'll be turning my attention to these in the near future.
My questions are about how best to proceed with insulation and air infiltration in the walls. The energy auditor recommended blowing cellulose into the walls through holes drilled in the interior plaster, and he also recommended blowing cellulose into the pent roof. Taking the three areas separately, how do you feel about ...
... insulating the stone walls on the first floor? (And does it make sense that the cavity really could be 3-4 inches or more? Are there 2x4's in there?)
... insulating the stud walls on the second floor?
... insulating the pent roof?
If you agree with adding insulation to any of these areas, what type of insulation would be most effective and least likely to interfere with the way the walls were designed to deal with moisture? I've recently learned of a concrete foam product named Air Krete, which goes in as a liquid and expands very little (less likely to blow out plaster or studs than other foam insulation). One strategy I'm considering is to use Air Krete in the second floor walls, and leave the stone wall cavities empty. I'm also inclined to leave the pent roof be.
If you disagree with adding insulation due to moisture concerns, how would you tackle the mystery air infiltration issue?
Thanks very much, and I look forward to your wisdom.
My house presents a slight variation on this theme. I have a 1920 Dutch Colonial, with stone on the first floor and walk-out basement, siding on the second, and a pent roof in between. The siding is currently foam-backed aluminum, covering the original wood (which appears to be in decent shape). I had an energy audit with blower door test, which revealed substantial air infiltration -- more than could be explained by the leaky windows and attic. The air could be felt strongly through recessed lights in the first floor ceiling, leading the auditor to suspect the pent roof -- though he could not find conclusive proof. He thought there might be open joists to the pent roof, although later inspection during a soffit repair revealed sheathing covered by felt running all the way down to the stone. Interestingly, the auditor estimated the cavity in the stone wall at 3-4 inches deep. For my own part, I removed an outlet in the baseboard of my dining room and measured 9 inches before hitting stone!
My first attention has been to the attic and windows. In spite of much conflicting opinion, I went ahead and had the underside of the roof deck sprayed with foam. Whatever other issues that may raise (hopefully none) air infiltration and heat escape should not be among them. The old double hungs are in pretty good shape, with those on the north side equipped with metal weatherstripping running in channels routed in to the sashes. I've been rebuilding and adding weatherstripping as needed. All of the windows have storms, including some with very old, very heavy, and very attractive double track aluminums made by Burrowes. Unfortunately, most of the second floor storms were replaced with standard triple tracks in the 70's, and I'll be turning my attention to these in the near future.
My questions are about how best to proceed with insulation and air infiltration in the walls. The energy auditor recommended blowing cellulose into the walls through holes drilled in the interior plaster, and he also recommended blowing cellulose into the pent roof. Taking the three areas separately, how do you feel about ...
... insulating the stone walls on the first floor? (And does it make sense that the cavity really could be 3-4 inches or more? Are there 2x4's in there?)
... insulating the stud walls on the second floor?
... insulating the pent roof?
If you agree with adding insulation to any of these areas, what type of insulation would be most effective and least likely to interfere with the way the walls were designed to deal with moisture? I've recently learned of a concrete foam product named Air Krete, which goes in as a liquid and expands very little (less likely to blow out plaster or studs than other foam insulation). One strategy I'm considering is to use Air Krete in the second floor walls, and leave the stone wall cavities empty. I'm also inclined to leave the pent roof be.
If you disagree with adding insulation due to moisture concerns, how would you tackle the mystery air infiltration issue?
Thanks very much, and I look forward to your wisdom.
I would try to find & seal up places where air infiltrates; to stop the air movement within your walls & ceilings. That sounds easier said than done and as you have already attended to the attic & windows you have taken care of the most likely area of heat loss. Perhaps your house is balloon framed with openings in the cellar that allows air to flow all the way up the walls to the attic like a chimney? If so closing up the stud cavitys in the cellar might make a major change in the drafts. I gather your house is essentiall a wood frame house covered with a stone facing on the first floor rather than a solid stone house (18" window wells) and timber framed? If I were going to insulate the lower stone walls I would use closed cell foam to stop moisture infiltration from the interior. I think the professional installers have perfected foam instaleation so there is little problem with expansion causing damage to the plaster. Your pent roof is a roof extension at the top of the first floor? I suppose that could provide an opening into your first floor ceiling if the interior side wall is not closed in. Don
1840 Limestone Farmhouse
-
crickhollow
- Posts: 6
- Joined: Wed Dec 06, 2006 11:50 pm
- Location: Western Maryland
- Contact:
Insulating attic (unvented wood shingle roof)
This may be my new favorite place on the web!!!
Help with my dilemma would be greatly appreciated.
I have a 200+ year old Maryland field stone home. My roof is wood shingle (Cypress) attached to ~ 1x1 inch think nailers which are of course attached to the rafters (combination of old 3x3's and newer 2x6's placed when metal roof was replaced with the wood shingles). There is no ridge vent or soffit for ventilation.
In the process of refinishing the attic we removed the drywall and poorly installed R-13 blanket insulation. We are left with ~5 inch deep cavities (~30-36 inches on center) that we need to reinsulate. Any recommendations?
Of course I want to pack as much R-value as possible into the small space AND am worried about the poor ventilation of my wood shingle roof (again, no ridge vent or soffit). I am intrigued by spray foam insulation which reportedly forms an airtight seal, therefore does not require an air gap or ridge vent/soffit. Is this true or simply a fairy tail? Any other viable options? I'd like to avoid retrofitting a ridge vent + soffit.
.....winter approaches....Brrrrrrrrr!!
Help with my dilemma would be greatly appreciated.
I have a 200+ year old Maryland field stone home. My roof is wood shingle (Cypress) attached to ~ 1x1 inch think nailers which are of course attached to the rafters (combination of old 3x3's and newer 2x6's placed when metal roof was replaced with the wood shingles). There is no ridge vent or soffit for ventilation.
In the process of refinishing the attic we removed the drywall and poorly installed R-13 blanket insulation. We are left with ~5 inch deep cavities (~30-36 inches on center) that we need to reinsulate. Any recommendations?
Of course I want to pack as much R-value as possible into the small space AND am worried about the poor ventilation of my wood shingle roof (again, no ridge vent or soffit). I am intrigued by spray foam insulation which reportedly forms an airtight seal, therefore does not require an air gap or ridge vent/soffit. Is this true or simply a fairy tail? Any other viable options? I'd like to avoid retrofitting a ridge vent + soffit.
.....winter approaches....Brrrrrrrrr!!
My stone farmhouse has a 100 yo standing seam metal roof installed over the original cedar shingle roof. It has no ridge or soffit vents. The walk-up attic has four gable windows which have screened vents installed in the summer & the lower sash are closed in the winter. The attic floor has insulation installed under it. The whole house retains its lath & plaster. Lack of roof/soffit ventilation doesn't seem to be a problem in this house but the unfinished attic is a rather large space. If your stone house is similar perhaps roof/soffit ventilation is of less concern? Closed cell foam insulation may be something to consider as it creates it's own vapor barrier. Don
1840 Limestone Farmhouse
-
crickhollow
- Posts: 6
- Joined: Wed Dec 06, 2006 11:50 pm
- Location: Western Maryland
- Contact:
Thanks for the reply. Don, your home sounds and looks quite similiar to ours, including 2 windows at each gable end.
The primary difference between our situations is that it sounds like your attic is unfinished with plenty of space for your shingles to breath, whereas I will be creating finished living space (bedroom actually) with drywall up the cathedral ceiling. So we will have this 5 inch cavity between the underside of the wood shingles and the drywall.
Do I fill the cavity with closed cell foam? If so, should the foam be directly in contact with wood shingles or with a 1-2 inch baffel? The only other option I can think of is R-13 or R-19 fiberglass batts with 1-2 inch baffel, but I'm not sure how effective the baffel will be without a ridge vent/soffit. Going the fiberglass route, what would be a good vapor barrier and to which side of the insulation would it go?
Thanks again for the reply. -Dustin
The primary difference between our situations is that it sounds like your attic is unfinished with plenty of space for your shingles to breath, whereas I will be creating finished living space (bedroom actually) with drywall up the cathedral ceiling. So we will have this 5 inch cavity between the underside of the wood shingles and the drywall.
Do I fill the cavity with closed cell foam? If so, should the foam be directly in contact with wood shingles or with a 1-2 inch baffel? The only other option I can think of is R-13 or R-19 fiberglass batts with 1-2 inch baffel, but I'm not sure how effective the baffel will be without a ridge vent/soffit. Going the fiberglass route, what would be a good vapor barrier and to which side of the insulation would it go?
Thanks again for the reply. -Dustin
Hi Dustin,
I see your problem. You are right, without soffit & ridge vents the baffles won't do much; the idea is that with the vents & baffels air circulation is created to keep the roof cool in the summer & cold in the winter. I would call some commercial foam companies and see what they recommend. If I were going to do as you plan but use fiberglass insulation I would still use the baffles (required by code in MA) install fiberglass bats then staple poly sheeting over the bats, strap the ceiling & install sheetrock. That doesn't solve the air circulation issue but it's better than nothing. Closed cell foam may still be the best alternative. Don
I see your problem. You are right, without soffit & ridge vents the baffles won't do much; the idea is that with the vents & baffels air circulation is created to keep the roof cool in the summer & cold in the winter. I would call some commercial foam companies and see what they recommend. If I were going to do as you plan but use fiberglass insulation I would still use the baffles (required by code in MA) install fiberglass bats then staple poly sheeting over the bats, strap the ceiling & install sheetrock. That doesn't solve the air circulation issue but it's better than nothing. Closed cell foam may still be the best alternative. Don
1840 Limestone Farmhouse