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Volume 4 Issue 4“Building Confidence”April 2006



Welcome to those new members to our site as well as to this newsletter. We are a bit behind in getting these newsletters out, please bear with us.

What's New

I've handed out a lot of advice through, but now I need some myself. For five days in May I was chosen to go to Mexico to investigate the possibility of construction work for a church camp in Rio Chico. I belong to the Shawnigan Alliance Church that is a member of the Christian and Missionary Alliance, which owns a church camp in Rio Chico, Chihuahua, Mexico. I went along with four other members of my church and our district leader. We indeed found out that there is a lot of work to do at Rio Chico. The first on our priority list is to build a water storage tank and filter system to improve the water for bathing, etc. The water is now being pumped from the river, which at this time of year is but a trickle. I have come to the conclusion that we could build a cistern from concrete and rocks to contain and store the water during the dry spell and treat this water with the use of a sand filter, whose outer shell would be made of concrete as well. If anyone out there has experience in this I would appreciate some information.

Ask Away!

Here are some of the questions and my answers for the month:

Dave I'm trying to figure area in square inches of an irregular rectangle
2 sides being of the same length which is 7.75, and the top is 8.75, and
the bottom is 11 7/8". i have several different area with different lengths,
so if you can give me this formula I would appreciate it thanks in advance
as this site is very helpful....... Thanks Brandy!

Hi Brandy,

This is a trapezoid (a four-sided figure that has two of its sides parallel to each other). Take the average length of the parallel sides. That is, add the two lengths (8.75 plus 11.875 = 20.625) and divide the total by 2 (= 10.312). The average length of your top and bottom is 10.312. Then multiply this average length by the height (10.312 X 7.75 = 79.922) to give the area. Here is the formula:

Area of a trapezoid = height X (top + bottom) / 2

Hi Dave, Lots of people "trim out" their windows different than others. What's your prefered way of installing window trim?

Hi Bob,

Are you referring to the inside or outside?

Hi Dave, Sorry for being so vague. The inside trim. After the "stool" is
installed, where do you start next? The top head or the side piece?

Hi Bob,

If installing a window stool instead of the picture frame casing, this is the way I do it. Install the stool first, have it extend beyond the vertical casing at least 1". Install the upper casing as normal. Install the apron, under the sill, with the ends of the apron directly under the outside edge of the casing.

Here is a drawing:

Diagram of inside window trim showing casing, stool and apron.

I have drywall return in my own home and did the window stoop and apron like this:

Photo of a window sill.

I have round circle head windows in the living room, family room, and foyer and kept that theme with my door casing, as shown here:

Photo of a pocket door.


Hi Dave, We are planning to add onto our existing 14x52 block basement (double its width). What do you think about wood foundations and wall. Our soil is pure sand and we are located smack-dab on top of a dry ridge. The drainage is great. All runoff flows away from the house. We are in northern Minnesota. Thanks, Rich

Hi Rich,

I don't have a problem with pressure treated wood foundations in dry climates. I put one in for a guy I built a house for in the interior of British Columbia, where it is quite dry. The next house I built for him he went with the conventional concrete foundation. Remember the depth you have to go to get below the frost line. A foundation wall not only holds up the house it holds back a fair weight of dirt, as well.


Dave, How are things up in Vancouver? Sunny here in Port Orchard, WA. I need some help. Since you are the "all-knowing guru" I know that you will have the answer. I'm thinking about having a "post & frame" "barn building" put for a garage/workshop. I like the idea of having a metal roof and metal siding and I frankly don't want to spend my whole summer building a stick frame building since I work 40 hours a week. My question: If I go this route; How do I frame it in so that I can sheetrock it. I want to completely finish it off inside so that it will be insulated and put in a forced air furnace so I can use it year around. According to the blue prints it will built with 8x8 post every 12 feet, with 2x6 cross bracing on the outside for the metal siding to attach to. The size of the building will be 32 feet X 60 feet long. I want to have sheetrock on the ceiling and walls for clean finished look. I have never really looked at "post & frame" building. Please give me some insite from your vast array of knowledge. Thank you, Kelly

Hi Kelly,

Yes, it looks like we finally got some good weather, about 22C, oops that's 72F in WA.

A post and beam structure is designed to get the roof up quickly, leaving spaces between the posts that can be filled with windows or large openings, or conventional framing, later. Since the walls are not solid, with studs to attach sheathing to, cross braces are needed to keep the posts plumb and prevent them from falling over. Horizontal strapping is required to fasten the vertical siding to, such as is required on the roof. The spacing of the horizontal rows of strapping depends on the gauge of the metal. To insulate a building such as this, there are large commercial size batts held together with foil or the builder needs to frame studs every 2' on center to allow the use of residential size batts. The design of the foundation must also match the position of the posts since the entire weight of the roof is supported on the posts not on a continuous footing.

In my opinion, in your case, wanting insulated walls and drywall, a post and beam building is going to cost you more time and money rather than going with the conventional stick frame building with studs every 2'. In our area the walls should be R-20 requiring 2x6 studs or a not so popular option of 2x4 with 2" Styrofoam on the outside. Rather than framing the walls between the posts you could use the framing as a continuous wall strong enough to support the roof without heavy posts or beams. Sheathing is not required, but 1x4 cross bracing is needed, let into the studs or on the outside face, instead of the sheathing. Strapping would still be required on the walls. Siding cannot be used to act as sheathing. Another option is to use 1"x 8" boards as sheathing which are considered heavy enough to accept fasteners for siding, eliminating the need for strapping. In this area we use 1x8 resawn boards for forming the foundation walls, then re-use the same boards as our wall sheathing.


Hi Dave, I live in Northern Minnesota. I am planning to build a new home on an existing basement. (28x52 home on a 14x52 basement). The problem is I want the home larger than the basement. Can I use concrete piers under the part that is larger than the basement and if so how should I skirt it and should I just insulate it and heat the crawl space? Thanks, Rich

Hi Rich,

Yes, you can do that, but I wouldn't, not in a cold climate. It would not be much more work or expense to put in a proper footing and foundation wall to increase the existing foundation. This way it is enclosed properly and a good supporting foundation. You need about 140 inches of frost penetration in Duluth and about 125 in Minneapolis. Wow!!

A crawl space is typically heated since the plumbing pipes are under the floor and need protection.


I am putting in a storm cellar and above that I will be building a 22x22 family room. How do I secure my TGI's for my floor to my basement walls? And or what would you recomend over tgi's?


I joists are an engineered product and installation should be followed exactly as specified by the engineer for that particular product. When the I-joists come on site they will include info on installation, handling, etc.

Usually with I-joists it is recommended to nail the bottom chord down to the wall or sill plate with a 3 1/4" nail, one on each side. A box or rim joist is substituted with 5/8" or 3/4" OSB nailed to the top and bottom chord at the ends of the joists. Standard 5/8" tongue and groove sub-floor in OSB or plywood is then used. I mainly use 5/8" T&G plywood for sub-floor, especially when hardwood flooring is attached on top, since it holds nails better than OSB.

Go with the engineers specs if at all possible.


Dave, I am building a hip front porch roof. It will be 24 feet long by 10 ft wide. If I use two 2x10 nailed together for a 24ft beam. How many posts will I need to support it. Also Should it be a continuous beam or two 12ft beams. Also, why is it recomended to place 3/4" plywood in between the 2x10's. Thanks, John

Hi John,

The maximum span for a 2x10 lintel made out of number 2 and better spruce, pine or fir with a snow load of 20 lbs per square foot is 9.45'. In your situation for a 24' span, I would go with 4 posts, breaking the span into around 8'. Use 2 - 16' lengths and 2 - 8' lengths of 2x10 with the joints over the posts, laminated so that the 16' goes with the 8', so there isn't a break right through the beam at the posts.

The 3/4" plywood between may give a bit more span, but span tables are not based on this. We may place a 1/2" plywood between members of a lintel to shim out the width to 3 1/2" instead of 3".

Dave, Thanks for the floor plans you sent. I was wondering if it is feasible or possible to take cedar siding and simply cut smaller widths to use as the roof, or is cedar roofing cut differently because of it being on the roof? Also the barn/storage shed I am building, I raised the height of the walls to 8 feet. The width is 12 feet, and the length is 20 feet. I read something somewhere on your site that I needed some type of bracing for lengths over 16 feet but I cant find it now...could you tell me or direct me to what needs to be added...maybe nothing? Thankyou for your help your site and knowledge is great!!!! Glenn

Hi Glenn, how's it going?

Cedar siding is not the same as shingles for a roof. Siding is tapered across the width in long lengths where shingles are tapered across their length in short widths. Cedar shingles are sawn to get a taper, where shakes are split. You buy shingles in bundles where 4 bundles usually equal a square which is 100 square feet. This makes it easy to estimate quantities.

For the shed: Notice that the gambrel shed without a loft has strongbacks of 2x6 on top of the long walls. This forms a 2" overhang but also acts as a wall stiffener. When a load comes on a roof it has a tendency to push out the walls without a tie across, like the bottom chord of a truss or the ceiling joist with a rafter. This strongback prevents that. For a 20' wall, I recommend to double up the 2x6 strongback as well as the 2x4 top plate. This makes a beam in effect which lays on its side to strengthen the wall, preventing it from bowing out.


Well, that's it for another month. Thanks for the questions. Happy Renovations!!


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