Building Confidence

Volume 9 Issue 12
ISSN 1923-7162

Welcome to Dave's Shop Talk's Home Improvement Newsletter of questions from our members on their construction projects, a Tip of the Month and a home remodeling article, both from our website at

What's Happening

Hope everyone had a good Christmas, Festival of Lights or Hanukkah and will have a peaceful and prosperous 2012.

Tip of the Month

Drill holes for nails near the ends of boards to prevent their splitting. Ref: Jigs 5: Table Saw Tapering Jig.

And a Bonus Tip:

Before drywalling over the cavity holding a pipe chase, place extra pieces of drywall around the pipe to soften the noise of water coming down the pipe. This applies to heating pipes, also. Ref: Plumbing and Ventilation 3: Questions on Plumbing and Ventilation.

Ask Dave!

Dave, I'm building cabinets to go above a kitchen counter. There is no window in the wall. How should I design the section that goes above the sink? How high should it be above the countertop? Should it be inset (not as deep as the other cabinets)? Thanks, Martin

Hi Martin,

If there is no window behind the sink, the wall cabinet should be 30" above the counter top and the standard 12" deep. This leaves an 18" high cabinet. The standard height of wall cabinets above the counter top is 18".

The wall cabinet above a stove is set at 30" making it 24" above the stove with the hood in place. This leaves the cabinets above the stove and the sink the same at 18" high and 12" to 12 1/2" deep with the doors of 3/4" beyond that.

With an 18" high cabinet above the stove, you have the bottom of the cabinet set at 66" from the finished floor and the top of the cabinet set at 84". This is the standard for an 8' ceiling. The top of the cabinets are either left with a 12" space or filled in with a 12" soffit.


Hi Dave, my floor joists are on 19.2" centers. I bought 24" insulation for the floor. Is it ok to just cut the insulation to fit? Thanks

Hi Andy,

Yes, that's exactly what you have to do. Cut them about 1/2" bigger than the measurement between the joists. The left over cutoffs can be used around doors windows, etc. and throw the rest in the attic.

Have a merry Christmas, you and the family, Andy.


I have a dual pane glass enclosed 3 season room off of my kitchen door wall sitting on a slab. The room is 2 ft lower than the kitchen. Can I run a heat duct from the house into the 3 season room? If we leave the door wall open on cold days the windows sweat from the humidity in the house. Will this happen if I run a vent to the room?

Yes, you can run a heat duct into the room. If you intend to close the door with the heat on, you should also install a return air duct. You need air movement to stop the condensation. You can't blow air into a room without a means to let it out. Spread out the heating and return air ducts.


Hi Dave, the attic trusses in my cottage are 2x8 between the ceiling and the knee wall (see diagram), which doesn't allow a lot of room for insulation. I am insulating (all fiberglass) the cottage roof at R-56 which is 17" of insulation. What should I do about the section of the attic truss which is only 7½"? Also, do I need to use ventilation chutes when I am insulating? Thanks

Hi Andy,

This is a very good question.

In a situation with a vaulted ceiling like this, you are required to strap the roof with 2x4s to allow for cross ventilation. This is something you should discuss with your building inspector. Of course, this needs to be done before the roof deck is applied.

Check out, in your area, if they have readily available a high density insulation for the 7 1/4" space. You may need to use Styrofoam at this location, whichever gives the higher R-value. Another option is to drop the ceiling, a bit in this location. Whatever, I'm sure you would need to strap the roof, though. It is important to check this out with the inspector.


Feature Article of the Month

(taken from our website:

Remodeling 16: How to Install a Prehung Door

Outside Prehung Door

First once you have the prehung door unit, verify that the size of the rough opening is correct. With a threshold, the height should be 84" for an 80" door. Without a threshold it is 82 1/2". The width for a rough opening should be 2" larger than the prehung door. Example, for a 36" prehung door the rough opening width should be 38". Some prehung doors come complete with brick molding on the outside, which goes against the sheeting. The width of the jamb should match the width of the studs plus the thickness of the inside finish and the outside sheeting.

Apply tar paper to the perimeter of the door opening, so a good overlap of 4" can be done when the wall is papered. Install the prehung door unit into the opening, snug the brick mold into the sheeting, with the prehung door unit resting on the subfloor. With shims or wood shingles split about 1 1/2" wide, shim the sides at the top so the more at

Almost the End

Well, that does it for another month. We hope some of these questions and answers will help you with your own projects. If you need more advice, join our website, then send me an email.

Thanks for your emails and support.


(Ask Dave) (About Dave)

Your source for building tips, woodworking & furniture plans, house plans and building advice directly from Dave...

Hi, I'm Dave Osborne. With over 50 years experience as a journeyman carpenter, foreman and contractor in heavy construction I enjoyed working with apprentices and sharing the tricks of the trade that others shared with me. Now I get emails from Members all over the world and we include many of my answers in our Free Monthly Newsletters. Some of my answers include drawings and instructions specific to a project, but may also answer your questions. I use correct construction terminology, so you can confidently inform your building supply dealers or contractors exactly what you need.


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