Building Confidence

Volume 15 Issue 10
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

Tip of the Month

Save nylons (panty hose, etc.) for straining paint.

And a Bonus Tip:

Use WD-40 to remove paint transfer from a vehicle bumper after a slight scrape.

Ask Dave!

Hi Dave. Perhaps you can advise me on something. I need to attach an 8' rough sawn 2x4 to the pitched cathedral ceiling on my double wide. I will be attaching a bi-pass cabinet door rail to that. I have no idea what the structure above the ceiling is like. I do have a closet frame to either side of the run that I can screw into but the 88" run seems like too much without some additional support. I have no idea what's above the ceiling (joists, etc.) that I could anchor to. Perhaps construction adhesive along the run would work? Anyway, any help would be appreciated. Thanks, Steve

Hi Steve,

Usually, in a modular they have low rise trusses. You should be able to tap the ceiling to feel for the spacing - probably 16" or 24" centers. Adhesive alone will not do it, try to get at least 1" of screw into the wood truss or ceiling joist. A handy tool for finding studs, joists is an electronic stud finder - good name!


I want to build a 3 season porch with windows and a screen door around front door to block winds and protect front door. If you look at picture you'll see that I have an overhang built into truss system of house. I am wondering if the deck foundation is enough and also wondering if I need to build walls in such a way that they can give? The soil is very stable -- packed damp sand but we do notice about 1/8" movement on that side of house between summer and winter. Built deck with 10.5' screw piles every 8' and about 7' away from house. We live in zone 2b. Gets pretty cold in winter and can freeze 8' down. We plan to break siding to put in walls then side the new walls after we tape seams and housewrap. We plan on insulating and vapor barrier-ing the structure but not heat it. Likely need to move some electrical too. Likely have to build a box at roof and below floor to hold insulation and plastic. Plastic to warm side. Any hints greatly appreciated! K

Hi Kate,

Thanks for the pic, it helped, lots.

Make sure your 4x4 posts are sitting on concrete blocks. You can purchase these "deck blocks" at building supply stores. They have a place for the 4x4 to slip into. Unfortunately, these may lift with the frost and thaw cycle, especially in your area, but going down 8' is extreme. I lived in a place where the temperatures got below zero and the frost level went to 8', as well. I built a slab on grade, for a shop, with 2' deep concrete perimeter. I would bank up the first snowfall around the perimeter and didn't have any trouble. Snow is a good insulator!

You should be able to put insulation under the porch, between the joists, then just strap it with strips of plywood, etc to keep it from falling down, or box it like you say - depending on the amount of R-value you want. Do not put poly under the insulation to hold it in place. Floors usually don't need a vapor barrier above the floor, the flooring acts like one.

For the walls below the deck, use a pressure treated bottom plate and studs, just above the dirt and use the metal siding/roofing as is existing. This would be good to pile the fresh snow against as added insulation. If you have any specific questions as you progress, just email me.

Hope this helps, a bit. You seem to have a good handle on your project.


Thanks for the reply Dave. Not sure what you're getting at re concrete blocks as I already have my 10.5' screw piles and 6x6 posts holding my deck beam up - that's our building code here and deck blocks only allowed in 2' high or lower decks or unattached decks. Our deck is attached to house and 3' off ground. I just want to wall above the deck to create a 3 season room to stop my front door from freezing up so bad. An advisor in a home building supply store warned of potential inside house drywall cracking should the deck and walls I have pinned between deck surface and overhanging roof should move differently than the house itself. Just wondered if you had a comment to that concern? I know in a previous house in a heaving clay environment, we devised a system so that the floor could move without affecting the walls in the basement, but that's a different house in a different environment. I just can't find info on walling in a deck with a pre-existing roof anywhere so I come to you. Anyways, thanks for the help! K

Hi Kate,

Sorry about the screw pile - I missed that. I never have used these. How hard is it to screw a pile like that down 10'?

It seems a shame to remove the aluminum soffit/ceiling, but the only way to insulate, if that is necessary. I'm thinking the ceiling comes about 7' out from the house wall. If you have access to the attic space you should be able to spread some vapour barrier to the gutter edge. You won't be able to get right up to the inside gutter edge, but close enough to get the vapour barrier in position with sticks, etc. then lay the insulation on top by sliding it on top of the VB.

Another thought: I don't see the point in covering the walls with drywall. I personally would side the walls with the same or similar vinyl ( it looks like vinyl in pic) as on the house wall. This is an outside enclosed porch, which in my opinion would look good with siding on the inside, as well as the outside - eliminates the problem of cracks in drywall or worst still moisture and humidity causing other problems over time.


Thanks Dave. The drywall question I had was really related to the pressures the new walls of the outside porch may have on the inside of my pre-existing house walls should there be some heaving on deck but not house. No, I wasn't intending on drywalling the new porch. And to answer your screw pile question, a machine turns the screw piles and the blade at the end screws into the dirt. See attached pic! K

Photo of a screw pile machine operating.

I learned something with this discussion - screw piles. Have any of our readers used these before?


Concrete House


Do you know how I might find information on building the walls and roof of a residential home from cement as they do in commercial construction? This seems like it would be an extremely strong and inexpensive building.


Concrete is not really inexpensive. The forming material alone would be the cost of the conventional framing. The roof slabs would require beams and posts to hold them up for 28 days. An engineer would have to be involved since it is not conventional. Forming pockets for plumbing and wiring through the walls and roof would have to be considered. Attachments for windows and doors would have to be allowed. Once built, it would last forever, though.

Most of the industrial buildings that I worked on were structural steel buildings with suspended slabs of concrete for the floors, the roofs were mostly steel as well. The buildings that were made totally of concrete were built that way for the structural strength required to support primary crushers and the like.

Commercial buildings including schools were built of concrete block with steel or timber roofs. I worked on high rise buildings that were mainly concrete construction. These are very expensive structures to build.

All things considered, I wouldn't advise building a residence out of concrete, there are too many better products out there. Concrete is best left to the footings and foundation walls.


Roy read the above article in last month's newsletter which brought forth his old memory:

The following took place more than 30 years ago, so things may be different now. My father-in-law was building a house in Tennessee. Wanting a basement to double as a storm/bomb shelter, he built it 90% underground with 12" concrete filled block walls and a 6" rebar reinforced concrete cap for the ceiling. He placed PVC pipe in the concrete of the ceiling to run all of his wiring. He was quite upset when the local electrical inspector failed his wiring as he could not 'see' that none of it was in contact with the concrete. The inspector said all of the wiring had to be run in conduit on the outside of the concrete. Roy

I would be upset, as well. We take photos of the install now, which is acceptable by some of the inspectors.

How times have changed!


No question Dave just want to say your site is awesome and I love how easy it is to get your rises and runs in the Calculator. And I'm sure I will be asking questions in the very near future. Please keep up the site it is great.

Thank you,


Feature Article of the Month

(taken from our website:

Roof 2: Calculating a Roof Pitch

Drawing showing a roof pitch and how to measure it with a steel or rafter square.Carpenters don't refer to the angle of a roof, such as 30° or 45°, but to the pitch of the roof, which is just the ratio of vertical to horizontal measurements. I say this because it's quite an important distinction. Angles are pretty hard to measure, but roof pitch is simple. An average and easy roof pitch to work with is a 5-12. The 5 refers to the rise of the roof and the 12 refers to the run of the roof. With the framing square (also called a rafter square) we can use these numbers directly without having to compute angles.

In your example of a 6' span or a 3' run (half the span) we could use a 2x4 for the rafters and a 1x6 for the ridge board. Refer to my article How to Use the Framing Square for some background information. For a 5-12 roof pitch take your framing square and with the 5 on the tongue and the 12 on the body with the heel of the framing square below the rafter, scribe along the tongue to give the plumb cut. From this point along the top of the rafter, measure 3'-3" and put another plumb cut at this mark.

Now measure back up the rafter 3/8", which is half the thickness of the ridge board. On the face of the rafter, square off a line from this last measure. This is the outside wall line.

For a tree house of this size a 6" overhang should be enough. So come down from this outside wall line 6 1/2" and scribe another plumb line. Scribe another line the thickness of your rafter trim, usually 1 1/2", parallel to this plumb line to shorten the rafter. Now go back to the wall line and scribe the bird's mouth and cut it out. This is the pattern for your rafters. Try two out first before you cut the rest.

One other thing when laying out rafters or joists or beams, always have the crown of the board up so it will straighten out with the weight of the roof.

Good Luck.

The above was taken from our article: Roof 2: Calculating a Roof Pitch

Thanks to all the questions sent in this month. Hope I was able to answer yours, as well.

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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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