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John Leeke's Historic HomeWorks™ Question & Answer Column

#13 Door Panels

We have a problem with our doors. The doors are various 4-8 panel doors. However the panels have a fair amount of movement within the door (back and forth between stiles, and up and down). Is this something we should glue tight? Or was this intended because of expansion. Any rule of thumb as to how much movement is too much? -- Andrew & Janyte Bullock, Middleboro, MA

The frame and panel system is designed to allow the panels to move. Wood expands and shrinks with changes in moisture content 10-15 times more across the grain than along the grain. The design keeps this movement within the panels making the overall size of the door more stable and less likely to jam in the door frame.

Generally you should not glue the panels in place. If a panel is shrinking enough to leave a gap between it and the frame, or if it shifts to one side it is possible to fix the panel in place and still allow for movement.

First determine which sides of the panel are end-grain. Usually it is the shorter sides, but if there is not much paint buildup you can confirm this by looking for minor striations or cracks on the face of the panel that indicate the grain direction. The end-grain sides are perpendicular to the grain direction. Center the panel in its opening and fasten it in place at the center of the end-grain sides with a single spot of glue or a thin brad. This will hold the panel in place and still allow it to expand and shrink at both sides.

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 thin skim coat. In some places the walls have been patched with an assortment of products (Plywood, drywall, cement...) I have preserved and patched one wall on the second floor that was in good shape. The same wall on the first floor I am taking down to the brick because it was in such bad shape. The other walls all vary in degree of separation. My problem is that all of the information I can find on repairing plaster talks about reattaching to lathing. I have no lath, and in some places the brick behind the wall has deteriorated into dust. What is the best approach to these walls? I don't want to remove all of the old plaster, but I don't think there is a way to reattach it. Any ideas or resources would be helpful. -- Renee Marshall, Annapolis MD

Before you do any more 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 relate to the interior plaster deterioration. Water may be penetrating the wall through these cracks or at other locations such as the roof and gutters or down near the foundation and cellar. As moisture migrates toward the interior surface of the wall it 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 before proceeding with plaster repairs. This might involve anything from minor gutter and downspout repairs to major foundation work to stabilize movement in the wall. 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 methods originally 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.

Lime Mortar Prevents Brick Damage

The mortar on our 1840s Victorian home is falling out and the bricks seem soft. I have heard that repointing with currently available mortar supposedly would crush the bricks as it cures. -- New Holland, Ohio

If used for repointing, modern high-strength Portland cement mortar will not allow for the inevitable movement in older brick walls. As the wall moves slightly the edges of the relatively softer bricks can be chipped off because the cement mortar is much harder than the bricks. The cement mortar repointing can also trap moisture in the wall causing it to come out through the bricks damaging them. Use a low-strength lime-rich mortar which is soft and will crack as the wall shifts. This cracking is acceptable because much of the lime remains "unreacted" and the crack will "heal" as it reacts with moisture and air entering the crack. A soft (Type "O") mortar with 1 part Portland cement, 2.5 parts lime and 8-10 parts sand may be soft enough. A very soft mortar is 1 part Portland cement, 4 parts lime and 11-15 parts sand. The key is to match the strength of the original mortar used in the wall's construction and for the mortar to be softer than the bricks.

© 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: johnleeke@HistoricHomeWorks.com; or log onto his website at: www.HistoricHomeWorks.com

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