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Volume 6 Issue 2“Building Confidence”February 2008



Welcome to all our subscribers, old and new. It is nice to see Spring just around the corner, welcoming in our building and reno season for another year.

Ask Away!

Here are the questions and my answers for February:

You use tar paper for moisture barrier under vinyl siding.same as felt
paper?we have 15 and 30 pound.which one?most people in my area use tyvek
housewrap.Is this better?
Thanks joe

Hi Joe,

The moisture barrier behind siding is a special breathable tar paper. It is listed in minutes of water penetration, such as 15, 30, 60, minutes. Roofing felt is a non-perforated tar paper which is listed by its weight, such as 15, 30, 50 pounds per 100 square feet (a square). Tyvek is a good product for walls, it also is breathable.


hey dave.  i am remodeling a house to sell.  part of the house has a
flat roof.  i had the roof inspected by a roofer.  he said that the flat
roof has some low spots on it where the rain will puddle up.  i noticed
that to be true after a rain. he suggests that the roll top be torn off
to the decking.  then he would run a string line over the flat roof to
show the low spots.  then he is going to put a stryofoam board on the
decking then he would put new roll top roofing on.  what is your
suggestion.  also what stryrofoam board do you think he is talking
thanks for your input.  the roofer is wanting to charge 3-4 thousand for
the roof job.  i have installed several roofs.  im just not a flat roof
expert.  thanks

Hi John,

Getting a roofer to inspect a roof is like getting a lobbyist to write his own laws.

I've seen many flat roofs under water with the drain at the highest point. The question is if the roof leaks. The roofer is giving you his opinion on a perfect flat roof. In my opinion, a flat roof is never perfect and will always have puddles, unless there is a slope to it. What the roofer is talking about is a type of SM ridgid insulation, common to roofs. You can walk on it without leaving footprints. There may be better, at least cheaper ways to correct your puddling problem. One is to put a slope on the roof. As a carpenter, I would not put a slope on a roof by using expensive SM insulation. I would use framing and sheathing materials.

With your background of installing several roofs, try to look at installing at least a 3/12 slope to be able to use standard shingles. Then you won't be dependent on a roofer for hot tar. I can probably help you with that, if you send me more info, such as pictures.


Hi Dave,
I have a garage pad 22L x 18W with a 2 inch slope. How do I frame the
so the top plate is level. Also how do I start the vinyl siding as I
have 2 inches to bring the siding down.

Hi Kelly,

Usually, the slab perimeter is level and the slope is inside of the concrete wall. In your case each stud has to be cut a different length so the top plate is level. The problem with this is any water running off the vehicle can go under the bottom plate, creating rot, rather than hitting a concrete wall and flowing toward the front. Either make sure the bottom plate is pressure treated wood or lay a course of concrete block level along the perimeter, or form up a small level concrete wall, there.

With a wood framed wall you need either 6" or 8" of concrete foundation wall above the grade for the frame to sit on. This lifts it above the elements of weather and bugs. You could start your siding on a slope and use a J-mold to trim it or you could use a belly band of 2" material tapered to fit the slope on the bottom. If you put in the 8" concrete block, that problem is solved.


I live in a house with a small open air atrium in the middle on the
top floor in San Francisco.  There is a really nice roof that I like
to sit on and read, and I'd like to build a Lapeyre staircase to get
up to it.  It's a 10' rise.  I've never built much in my life,
so don't know basic things.  I saw the picture on the site and can't
tell how to attach the stair treads to the stringers.
I assumed I would cut out 90-degree cutouts in the stringers and lay
the treads on, but the picture looks like the treads are just nailed
in from the sides.  Doesn't look that strong.  Can you help?
Thanks, Elliott

Hi Elliot,

Here is the instruction from the article:

I allowed the tread 1" longer so he can dado the stringers 1/2" on each side. This will be stronger than just the treads screwed to the stringers as in the picture. Also, I told him to put the handrails on the inside of the stringer, as specified by WA code, not like the picture having theirs on the outside. The end cuts and treads are on a 19 degree angle, so the length will fit. Where the 5" side of the tread is on the stringer, just rip a small filler to fill the dado. A blind dado would also work, here. The treads on the angle should be a bit longer than the width of stringer to fill in the dado nicely and overhang the stringer a bit.

The picture of the Lapeyre stairs, as mentioned in my article, has 3 things that need improving. The hand rails should be on the inside rather than the outside and the treads should be dadoed in rather than just depending on screws to hold the weight, as you suggested and the treads should be wide enough to overhang the stringer a bit.

I think you misunderstood the term dado. We have a Construction Dictionary on our site which explains terms like this. You can find it at:

Most words like this are highlighted in my articles and plans, with links to the dictionary. For some reason dado is not highlighted in this article. A dado is simply a groove in a board. So in this sense, the treads are placed into a groove that is made in the stringer. The stringer is not cut out like a normal stair stringer since the stringer is very narrow and cutting out the tread would weaken the stringer too much. Another way to do this is to screw the treads through the stringer and install a cleat under the tread, screwed into the stringer, about 3/4x1 1/2. This may be easier for you to do if you don't have dado blades or power tools.

If you need help with the math on the layout, just let me know.


Here is a picture of a member's stairs that I helped with which shows the dado clearer:

Thanks, Dave.
Does it matter whether you use screws or nails for the treads and cleats?
What size should they be?  And how many do you put in on the 5" and 9"
sides? How much weight will these steps hold without the dado grooves?

One other question: I may have enough room to do regular (but steep)
stairs instead of the pure Lapeyre.  It would be more like a hybrid,
where I'd cut stair stringers, but have it be steep and use side rails.
At what angle would it be ok to cut out the tread in the stringers without
weakening the stringers too much?  (My assumption here is that the stairs
would be a lot more stable than the pure Lapeyre if I have enough room).

Hi Elliot,

Screws are stronger than nails, glue and screws is the best. When screwing 3/4 cleats into 1 1/2 use at least 2" screws, 2 1/4" max. For treads use 3" screws as well as glue. Use 3 screws in each tread and cleat x 9" and 2 for the 5" side, spread them apart. When I was an apprentice, I learned that a 3 1/4" common nail driven into good fir on the vertical will hold 300 pounds. So weight isn't an issue it is keeping the cleat or tread tight to the stringer. Nails alone loosen up over time. This is why we design a structure to not depend on nails alone.

If stairs are too steep a problem is created coming down the stairs more so than going up. The rule with stringers states that a stringer should not be cut out more than 3 1/2". Sometimes you can use a 2x10, other times you need a 2x12 in order to have 3 1/2" left under the treads.


hey dave.  I am getting ready to put vinyl siding on a home i purchased.
does it matter if i do the soffits before or after the walls.  This is
my first time with vinyl siding.  i appreciate your articles very much.
if you have any pointers that i should not forget, please feel free to
advise me.  I planned on purchasing at lowes,  or do you know of a
cheaper route.  i am selling the house as soon as i am finished

Hi John,

I prefer to install the soffits firsts, but you can go either way. One thing that you should not do is nail the soffits supports to the vinyl. This stops any expansion and contraction of the vinyl. It is much easier to install the soffits first.

Checkout both my articles on soffits as well as the siding, pay particular attention to expansion and contraction of vinyl and aluminum.

About where to buy: I thought the big box stores were cheaper overall. This is not the case. I did a reno for my daughter who lives in a large city with all the box stores. I gave her a list of materials and told her to get some quotes. She got about 10 quotes. The most expensive was the box stores. The local building supply stores had the best prices and service. Don't just go by their shelf prices. Go to the contractor desk and present them with a typed out list of materials. This way you get the best price based on quantity. Some building suppliers will even take quantities off your plans for you, free of charge. I prefer to fax around a request for prices to keep everything even. Maybe talk to the contract sales people first to get a feel for the way they prefer to do business. Even if you have an account at your favorite store, still get a price quote on any decent size of job. This way they offer you the best price.


Do you have any plans or do you know where I can find plans that will
help me make a router table?

Also, was just looking at the circular saw jig.  My problem is that I am
a TRUE left-handed person. Hardly able to use my right hand at all. Any
ideas for me?

Hi Fred,

My router table is a work table on the back side of my table saw. I just removed the base plate of the router and screwed it to the underside of the table. Like using the table top for a huge base plate, except upside down. The table is 3/8" plywood, not too thick. I leave the base in place under the table, most of the time, dropping the arbor when not using it. I use a 1x3 straight edge as a fence, screwed or clamped to the table top. It works great for cabinet doors when routing their edges.

You could use the shop work bench/table as a pattern for a large router table, like I have. Use either 3/8" plywood if used as a receiving table for a table saw or router the 3/4" ply or MDF to 3/8" thick under it, where the router base will fit.

My brother was left handed. He helped me frame my duplex, but I didn't watch him cut with the circular saw. He didn't mention any trouble he was having nor did I think about it. He helped my daughter tie her shoe laces herself when the way I showed her didn't work. I'd love to ask him for you, but he died from cancer in 2003. I think this is the first time someone asked me a question that I couldn't answer. If you know a friend or relative that is left handed, maybe ask them to demonstrate for you. When you find out any tips, I'll pass them onto our members. Actually, we have over 10,000 readers for our monthly newsletter, someone should be able to answer your question.

I don't see why the circular saw jig won't work for lefties, as well. Are you aware of a circular saw with the blade on the left side? I don't know if they would help or not.

I'll let you know if I get any feedback from the newsletter.


Can anybody out there help Fred with any tips for using a circular saw with his left hand? Please reply to this email. He would appreciate any input.

Well, that's it for another month, hope you get a chance to do that project you've put off all winter.


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