John Leeke's Historic HomeWorks™
	207 773-2306      26 Higgins St. Portland, ME  04103
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John Leeke's Historic HomeWorks(TM)

Foundation Regrading

I've been reading in several books that the ground should slope away from my 90 year old house. There has been a good deal of earth settling, causing water to flow toward the foundation and right into my basement. Could I use wood chips and other kind of mulch kind of materials or should the fill be soil? -- David Wright

Wood chips can attract carpenter ants and termites. The chips will not really solve the problem since water will simply trickle through them to the soil beneath and still flow toward the foundation. You need a two-step procedure of repairing any damage to the foundation and regrading for a positive slope away from the foundation to improve drainage. Dig several 1 foot deep holes against the foundation to look for mis-alignment of the stones or bricks and open joints between them. If they have shifted position this is a job for a mason with old-house experience. Dig a trench at least 1 foot below the existing grade, reset shifted stones, and repoint open joints with soft lime-rich mortar. Often clay-soil is recommended for fill around a foundation. You have to be careful though because some clay is very expansive when it gets wet. If you put in a bank of clay 1 or 2 feet wide or deep it could push your foundation out of alignment. We use a clay layer no thicker than 4 to 6 inches. The clay layer is underground. One edge of the layer "seals" to the foundation (especially good if it is an irregular stone foundation) and slopes away from the foundation 4 to 5 feet. Landscaping suppliers carry a powdered clay in bags. It is easier to spread out than clay-soil which lumps up in big clods. On top of the clay layer is 10 or 12 inches of loam soil which is also graded to slope 5 to 10 feet away at a rate of from 1:5 (1 vertical foot to 5 horizontal feet) to 1:10. The finish grade at the foundation should be 6 to 8 inches below any woodwork. Then we lay sod or establish a thick grass turf right up to the foundation with no flower gardens or bushes within 15 feet of the foundation. This allows efficient mowing of the grass. The grass does as much as anything to keep water out of the foundation because the roots catch it and put it back into the air. Keep foundation plantings of shrubs and flowers far away from the foundation which makes them more visible from the house.

Chimney Joint

I have a question concerning the removal of 1930s cedar shingle siding from our 1885 house, which we are returning to its original clapboard siding underneath. On the back of the house is a chimney, added in 1940, laid right against the cedar shingles. It's obviously impossible to get off the shingles behind the chimney, so I'm wondering what the cleanest way would be to deal with the transition between the clapboards and the shingles behind the chimney. I've tried to cut a straight edge with a knife, through the shingles and the paper sheathing, but it's a little ragged and I wonder about moisture getting behind the shingles. There's probably a distance of 3/4" between the face of the clapboards and the back of the chimney, so caulking does not seem to be practical. Any suggestions? -- Roger Clements

3/4" joints can be successfully sealed using a system call a "designed joint." The seal is created with a flexible foam rubber-like strip, called backer rod, that is stuffed into the joint first. Then the sealant is caulking-gunned into the joint. Then the surface of the sealant is tooled for a concave shape. This forms an hour-glass cross-sectional shape to the sealant. It is wide at the sides for more contact and better adhesion with the insides of the joint, and narrow in the middle for more flexibility. You have to use special high-performance sealant because most ordinary caulks don't have enough flexibility. The big trick in your case will be getting the inside surfaces of the joint clean enough. You can probably get the shingles out of the joint at least an inch back. Both sides of the joint must be thoroughly cleaned with a wire brush, scrubbing with TSP and water, then rinsing with water. For a longer lasting treatment consider flashing, especially if your chimney has soft mortar or needs repointing. You could work step- and counter-flashing from the bricks to the clapboards. Rake mortar out of the joints 1 inch deep and back 3 inches from the clapboards. Cut a vertical slot with a skill saw through the clapboards up along both the sides of the chimney. Loosen the freed ends of the clapboards slightly and work the step flashing under the clapboard ends and out through the slot. As you go along lap counter-flashing out of every second or third mortar joint over the step-flashing. This would require a craftsperson skilled in masonry repointing, sheet metal flashing and woodworking.

For more information on designed joints and sealants order Leeke's Practical Restoration Report, Exterior Woodwork Details (10 pages, $9.95, 207 773-2306) which lists suppliers, illustrations and more details.

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

Return to Q & A table of contents.

	John Leeke's Historic HomeWorks™
	207 773-2306      26 Higgins St. Portland, ME  04103
	[Home][Library][Restoration Reports][Seminars][Forum][Internships][Office][Workshop][Front Porch][Search] info.© 1994-2011 JohnC.Leeke