Resources for Historic Homeowners

John Leeke's Historic HomeWorks™ Question & Answer Column

#11 Plaster on Brick

Our house is a small one bedroom federal brick house built around 1774. All of the walls are brick and plaster. In many places the plaster has separated from the brick, creating bubbles away from the wall. The plaster is between 1/2" and 3/4" thick, with a horsehair rough plaster and then a skim coat. In some places the brick behind the wall has deteriorated into dust. What is the best approach to these walls?

Before you do any repairs to the plaster you need to determine what is causing the deterioration. Causes will be related to movement and moisture. There may be structural movement within the wall. Look for patterns of cracks on the exterior of the wall that are near the interior plaster deterioration. Water may be penetrating the wall through these cracks or at other locations such as the roof and gutters above or down near the foundation and cellar. As moisture migrates toward the interior surface of the wall it can deteriorate the mortar and the bricks, reducing them to powder. Even if the bricks and mortar are in good condition the moisture can loosen the bond of the plaster to the wall. If liquid water is penetrating it can dissolve the lime or gypsum that holds the plaster together resulting in loose and crumbling plaster.

Correct any moisture and movement problems and repair the brick masonry before proceeding with plaster repairs. This might involve minor gutter and downspout repairs to major foundation work to stabilize movement in the wall and brick and mortar repairs to the wall itself.

Reattachment of the plaster is possible but usually justified only when the plaster has some particular importance such as an unusual texture that cannot be easily reproduced or decorative paintings that must be preserved.

If you have more ordinary plaster the deteriorated areas can be removed and filled back in again with hand-troweled plaster with the same materials and methods originally used. The same two-coat plaster system should be used. If you cannot find a plasterer who knows how to do this, or just want to try it yourself start with the book "Plastering Skills", by F. Van Den Branden and Thomas L. Hartsell.

Window Sash Tracks

I have heard of a sash repair kit, basically you remove the molding and remove the window sash and replace the sash channels with those of the kit. The springs are behind the channels to keep the window open and there is some give to the channels so the window will raise and lower. I can't seem to locate the supplier for these kits. -- Archer Yates, Arden, North Carolina.

Narflex makes just the product you need. Their Tilt Sash Balance not only provides you with a new spring balance feature, they also allow you to tilt and remove the sash for easy glass cleaning and sash maintenance. The 3 1/2" wide vinyl extrusions are installed vertically against the window frame. A typical installation requires cutting 3/8" to 5/8" off both side stiles of the wooden sash. This is a simple table saw operation. Contact:

Narflex Window Company
7959 West Grand Ave.
Elmwood Park, IL 60707-1883
708 453-4043

Trimming away more than 25% of the width of the side stiles could weaken its joints. Trimming might not be appropriate if you are trying to preserve the historic value and character of your windows.

Replacement Window Glass

I am an old house owner and I am looking for a source of cylinder glass for my old windows. I plan to try the local salvage yard, but wanted to know if you knew of any other sources. -- Jim Black, Hatfield, PA

Try the following reproduction glass suppliers. Consider sending them a sample of your glass and having them send you a sample of their closest match.

Blenko Glass Co., Inc.
P.O. Box 67
Milton, WV 25541
304 743-9081

S.A. Bendheim Co., Inc.
61 Willett St.
Passaic, NJ 07055
800 221-7379

© John Leeke


John Leeke is a preservation consultant who helps homeowners, contractors and architects understand and maintain their historic buildings. You can contact him at 26 Higgins St., Portland, Maine, 04103; or by E-mail:; or log onto his website at:

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