Help we bought a wicked old house!!!

Old 11-30-05, 05:42 PM
Katherine Ellis
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Unhappy Help we bought a wicked old house!!!

We just bought a house built in 1700. All of the walls have horsehair plaster and we would like to put a skimcoat over so we can hide some of the cracks. But we don't want to skim coat only to find out a month later that the cracks are back. So we were just wondering how we could be crack-free and do it right the first time!! We know that its not going to look new but we'd like to make it as "pretty" as possible. The house was never registered as historic so we have full reign to do what we want. Thanks

Last edited by Katherine Ellis; 12-01-05 at 07:24 AM.
Old 12-01-05, 06:44 AM
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Where do you live? If your house is really built in the 1700's then it must be on some sort of historical listing. And if that is the case then you might have to keep it original. Meaning you can repair it but the way you do it has to be a certain way.
Old 12-01-05, 07:30 AM
Katherine Ellis
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old house

We just bought a house in Rockland, Mass. The house was never registered as historic so we can do what we want with no restrictions. We want to keep the character of the old house but give it a little updating and pretty it up a bit. Like i said the horsehair plaster is cracked in places and we don't want to skimcoat just to find out our efforts were futile. I would imagine that in the past 300 years it has settled to the point where its not going to settle any more and hopefully this will be an easy project. (ya right)!! Any info will be appreciated -Thanks Katie
Old 12-02-05, 07:37 AM
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Hi, I am editing this to mention that there is a slim possibility that your plaster may contain asbestos and you may want to have it tested before you start cutting and/or sanding it. Also be aware that if there is paint on the wall it is likely to contain lead, so you might want to take precautions when sanding and cutting for that reason as well. As for myself, I try to be aware of the issues and use common sense procedures (screening off rooms with plastic, minimizing disturbance of all materials i.e. not sanding any more than necessary, cleaning up with damp cloth and/or using a HEPA filter in the ShopVac, keeping kids out of the area and wearing a respirator) in all work I do in this old house, but I try not to freak out , as people have been living with this stuff in the house for nearly a hundred years and I have yet to find any bodies. Today's miracle materials become tommorow's toxins and even wood dust poses some dangers if not handled properly.

If historical accuracy is not an issue, the following approach should work. It is what I did several years ago and it appears to be holding up well. First determine if the plaster surface is delaminating from the lathe below (likely wood strips running behind the plaster). The plaster should be firmly attached to the lathe and not move if you push on it. If it moves, it is likely delaminated and simply patching will not last (see instructions in the following paragraph). If it is firmly anchored, then notch out the crack to form a v. Tape with drywall tape ( I prefer mesh tape) and fill with joint compound. For very small cracks or spider web cracks that go in every direction, I just cover the whole surface with the tape and mud it, not worrying aout the notching. You can also buy sheets of mesh or paper which cover the entire wall in this manner before skim coating, but this is relatively expensive. If the walls are bad enough to need this, I would likely tear out the plaster and replace with drywall.

If the plaster is separating from the lathe in places, it means that the keys (the plaster which is pushed through the cracks between lathe boards and forms a bond with it) are broken. In this case, there are two possible approaches:

1) break off the loose plaster and repair as you would a hole. To do this, you can either repair with plaster in two coats,or repair with drywall and mud. For the plaster approach, reform the keys in the scratch coat by pushing the scratch coat plaster through the spaces between lathe boards, and then finish with a finish coat. For the drywall approach, find a piece of drywall close to the thickness of the plaster and anchor it to the lathe in the hole with screws or glue. Then tape and mud as if you were doing a drywall patch. As the old plaster is typically very dry, I dampen it and the lathe before doing the repair, to ensure it does not suck all the moisture from the mud casuing it to dry too quickly, creating cracks.

2) You can reattach the delaminated plaster. There are two ways to do this. One is to use plaster washers and screws (look on the internet). The other approach to securing the delaminated plaster is to drill a grid of holes (about one inch spacing vertical and horizontal) just thorugh the plaster in the delaminated area, stopping at the surface of the lathe. Then inject liquid nails or other construction adhesive betwen the plaster and lathe to hold the plaster. You have to prop it up with a board supported by sticks of some sort while it drys. There is a website showing this procdure on a ceiling, but I don't have the address handy. It is apparently an approved restoration procedure for old plaster. You can probably find it by googling "restore sagging plaster". Then repair the cracks as above.

If you patch with plaster be sure to use a bonding agent to hold the new plaster to the old. I have not found this necessary when using mud. I have used the mud because I am more comfortable with it, it has a longer working time and is sandable if I overdo it, but plaster is harder and might bond better in the long term. Obviously the above methods take care of the rough repairs, which would then be covered with a skim coat. Techniques for skim coating are well discussed on this forum and the one under interior walls. I also apply a good sticky primer before painting, becasue you will be asking the paint to adhere a variety of surfaces and you might get bleed through from previous coats of paint and or stains on the wall. As I say, I repaired several walls this way and I believe they are quite "pretty"

One other tip is to get a shop vac drywall sanding attachement and a shop vac with a dust filter to do the sanding. It sucks up most of the sanding dust very well. I find that the drywall sanding mesh used on these things tends to leave little scratches in the surface, but less so if you sand in a diagonal direction. And the primer and paint seem to cover the scratches fairly well.


Last edited by guest2; 12-02-05 at 09:35 AM. Reason: forgot to mention asbestos and lead

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