remove plaster and lath on exterior to add insulation?

13 years ago

We are doing a total renovation on a 1927 tudor in Seattle, and were not too surprised to find that there is zero insulation in the exterior walls. The exterior of the house is a thick stucco with gravel mixed in, and the interior is plaster and lath. We have considered removing all of the plaster and lath and adding insulatation batts, but are now re-thinking and wondering if the cost and huge mess will outweighs the lack of R-value if left alone. Our climate is generally mild, and we are replacing the windows with new ones as well as adding attic insulation and new furnace. I am curious to know the thoughts of insulation experts about which way to go. Incidentally, the plaster on the interior is in good shape and would only require a skim coat for appearance if left in place. Thanks!

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Comments (9)

jemlafoy
Original Author
13 years ago
OOPS! That should read : "remove plaster and lath on INTERIOR"!!!
User
13 years ago
How about checking on the cost of having insulation blown into wall cavities? A small hole(easily repairable) at the top and bottom and cellulose insulation installed.
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"My general contractor offered me to hang a drywall on top of plaster but I dont see a value of this." Oh for the love of God - I wish if people didn't know how to do something or it was outside their range of expertise they would just say so and not propose these ridiculous things that do more harm than good. So he adds more thickness with a layer of drywall - what does he do with the trim then? Rip it out and install skinny cheap modern trim from Home Depot (some do exactly that - ugghhhh) Sorry OP I just had to vent there!! Ive been looking at old houses to buy and theres no end of goofy, futzy things that people have done to them. Im glad you saw the folly of that esp in such an old house. Like fine antiques, as time goes on people more appreciate the old things - esp if well maintained in original condition. You may want to go over to thehistoricdistrict.org, which has many old house lovers on the forum including professionals who can advise in great detail about how to do plaster repair. Especially with your age of house - you might want to confirm what type of plaster you have . There was an earlier type of lime plaster with different composition with materials you might have to hunt for (but certainly are obtainable at reasonable cost) The later type of gypsum based plaster used in early-mid 1900s - materials not available at big box - I think Ace had a type of patching plaster that can work but the plaster of paris that they (and home depot) sells is not good - sets up way too fast and hard. Otherwise any small-mid size city should have a building supply store where they carry the more specialized types of materials - while traditionally plater walls had a three coat system, for repairing cracks Ive just used plain patching or veneer plaster - if a bigger hole you can get a rough coat plaster for first layer and veneer plaster for the top layer. Use a bonding agent on the edges of the old plaster and the lath to help the new plaster adhere well to the old. There's various other techniques for bigger areas and different types of situations - and other people will have their favorite methods and materials (some use drywall compound but IMHO if you have extensive repairs its best (and considerably cheaper) to get the real stuff. Re very fine surface hairline cracks - ignoring those works the best! In a nutshell - plaster repair is exactly the kind of labor intensive but very doable thing that a typical home owner can learn to do, and do well.
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"I'm not entirely sure they are lathed - some of our internal walls had plaster attached to rock lath/gypsum board, but I'm not sure this was used on exterior walls?" 2-coat plaster (16x48 inch gypsum base) was used on all walls. In masonry houses interior plaster was often applied directly to the masonry of the outside walls (special blocks were made with grooves molded in to allow the plaster to bond). A large area of plaster that has come loose can be fastened back down if there is wood in the wall (studs) to drive long enough screws into. Plaster washers and long enough screws are used to pull the plaster back tight, and then the area is covered with another coat of plaster to conceal the washers. If the bulge is more than about 1/2 inch high it is likely to need to be removed, the substrate repaired, and then the area patched. Setting type joint compound (Durabond or Easysand) actually work well for repairing plaster. A bonding agent is still required (just as with plaster) to prevent moisture form being pulled from the patch before it sets correctly, but setting compound mixed about as thick as peanut butter (smooth please) has very little shrinkage as it sets (even in thick and large repairs). White Elmer's glue cut 50% with water and then painted on makes an excellent bonding agent. Just paint it on old plaster edges and surfaces, allow it to dry to tacky, then put setting compound over the area. The first coat does NOT need to be smooth, just below the final desired surface by about 1/8 to 1/4 inch. Further coats will smooth out the repair and make it level and even with the old surface at the edges.
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We are considering rehabilitating my husband's grandmother's 1850's home. I was told it's best to retain the plaster and lath so that the wooden baseboard trim lines up correctly. Also, I'm told it muffles noise better. But I guess if you busted it out, you could place the drywall at the correct depth? And insulate behind? The plaster ceilings have leaked, and refinishing all the plaster is going to run $2,000 per room. A home rehabilitation person said not to blow in insulation with plaster walls, as it is a magnet for moisture. Is that true? Good luck, Leanne. Hope you enjoy your lovely home!
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joed
13 years ago
In my opinion plater walls are much better than the drywall you will end up with. Have some sort of insulation blown in and repair the small holes afterwards.
jemlafoy
Original Author
13 years ago
Thanks handymac and joed. I have heard that blown in insulation has the tendency to sink/settle at the bottom of the walls and can trap moisture etc down there. What is your experience? Also, this particular stucco is very "old school" in it's texture, and even has crushed oyster shells in it. It would be somewhat difficult to match, and my understanding is that the holes would have to be every 16" on the entire perimeter.
hendricus
13 years ago
Do the work on the inside and patch the plaster walls.
brickeyee
13 years ago
" I have heard that blown in insulation has the tendency to sink/settle at the bottom of the walls and can trap moisture etc down there. "

Cellulose insulation does not "trap" moisture.
newenglandbuilder
13 years ago
Cellulose insulation will settle to some degree, but the R-value retained even after settling is far superior to what you have now. In addition, cellulose adds some measure of air sealing as well; you will notice the difference as you do each room, especially if you are replacing the windows.

Whether you have windows replaced professionally or doing it yourself, make sure that the window sashes are caulked properly after installation ensure proper sealing. A poorly installed window will negate your investment in the product.

Also, it is not impossible to match textured plaster finishes. Look for someone in your area skilled at plaster work, review them carefully, ask to see their previous work, ask for references -- and CALL THEM.

I've hired plaster finishers to to patching when we've remodeled areas that have sand or other texture and a good one is worth his/her weight in gold. It is not impossible, but it takes skill.

Don't destroy your original plaster if it is in good condition, it will provide a durable and unique finish and I would say that its uniqueness has historic value. Oyster shells in the finish are pretty darn unique I'd say and you should be proud to have such a treasure.
sierraeast
13 years ago
Since you plan on skim coating the interior walls anyhow, it would probably be better to do the insulation port holes on the interior side, patch when done, and skim coat away. I would stay away from the exterior and not mess up an original works!
Billl
13 years ago
Before you dive in, you should contact a local historic preservation society to see what is recommended for your area. They have extensive experience with the issues surrounding older homes.

Frankly, in your climate, I'm not sure this is a cost effective renovation. Your heating/cooling costs are presumably pretty low. If you spend thousands to insulate the walls, you might not recoup that cost for decades. In older homes in temperate climates, you typically will get a bigger bang for your buck insulating attics to the max and sealing up any place that air can flow for everything else.

remove plaster and lath on exterior to add insulation?

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jemlafoy
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remove plaster and lath on exterior to add insulation?

Comments (9)

jemlafoyOriginal Author

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joed

jemlafoyOriginal Author

hendricus

brickeyee

newenglandbuilder

sierraeast

Billl

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jemlafoy
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jemlafoy
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