It’s Easy to Build Shaft to Skylight
Question I will be installing a skylight in my living room, and I’m a little confused about whether I need a light shaft, and how to go about constructing one. Can you shed some light on this?
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Answer When you are dealing with a ceiling other than a cathedral, you will have a space between the skylight unit and the ceiling below. The size and shape of this light well or shaft depends on the construction of the roof and ceiling, the desired amount of light to enter the room and the appearance of the entire area.
If you want a light shaft, simply frame out the area between the roof rafters and the ceiling joists with appropriate lumber.
Keep in mind that this shaft can be designed to extend straight down into the room or be aligned perpendicular to the roof opening so it comes into the room at an angle. Box in the shaft with plywood, drywall or paneling. Finishing off with white paint will help reflect exterior light into the room.
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Q My brick house is about 20 years old. It has a concrete porch about 5 feet square with steps going down to the backyard. The steps and the porch have settled and pulled away from the house, leaving about an 8-inch gap at the top. The foundation goes deep underground.
Even if I could find a house jack big enough, I couldn’t fill in under the porch foundation. There’s no opening under the porch slab and steps to build a form. What can I do to solve this problem besides move?
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A If you are certain the porch is not still settling (if the gap is not getting wider year by year), you can fill in the gap between the steps and the house foundation wall starting at the bottom where the gap is narrowest.
Wedge a 2-by-8 board vertically against each end of steps to hold the repair concrete in place until it sets. Carefully fill the space between the house and the porch with concrete and compact it by poking or rodding it with a hoe handle to make certain it has filled the gap.
Finish the job by smoothing the top flush to the top step. Where the edge of the patching meets the wall, finish the joint with an edging tool. This leaves space for final sealing with a good grade of silicone caulk. If the joint continues to enlarge, the only permanent cure is to remove the porch entirely and rebuild it on proper fill.
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Q My foundation is made of 10-inch concrete block up to ground level and then a 6-inch block above that point with a 4-inch stone facing. The inside surfaces of the outer wall are plastered directly onto the block. These walls feel cold to the touch.
I recently visited Florida and saw several similarly constructed houses, but their block walls were covered with sheets of insulating material, furring strips and plastic vapor barrier. Would adding insulation and a vapor barrier solve my cold wall problem?
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A It sure would, especially if you install drywall over the insulation and vapor barrier. First, check the type of polystyrene you use. Some are effective water barriers in themselves.
The ability to deter the passage of moisture is measured in perms. Any material having a rate of less than 1.0 is considered an effective vapor barrier. Styrofoam brand insulation has a perm value of 0.6 for each inch of thickness. Since polyethylene (plastic vapor barrier) film is inexpensive, you should use it to ensure a continuous vapor barrier over gaps and joints in the insulation.
To submit a question, write to Popular Mechanics, Reader Service Bureau, 224 W. 57th St., New York, N.Y. 10019.
