Skirting in Pier/Beam construction

Started by Chateau Prideaux, September 04, 2006, 07:56:36 PM

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Chateau Prideaux

I've heard of skirting on a Pier/Beam foundation, but I've yet to see detailed pics. Can the brains weigh in on whether it is necessary and how it should be done on a sloped site?

I'm in central Texas with mild winters but exceptionally hot summers (a month + of 100+ degree days), so I'd like to get some ideas on how to properly insulate the pier/beam as well.

Thanks!
Quidquius Operat

Doug Martin

I posted the following in a thread back in January but I didn't spark any discussion.  Here is my idea:

Connect the foundation posts with a 2x filler "wall" over a gravel trench and then screw the blueboard insulation to the filler wall.  You could then attach diamond mesh to the blueboard and trowel on fibercement to make a flexible but hard shell.  Then fill the trench around the wall with 12" of gravel and I think your would have all the benefits of a continuous foundation along with the insulation value of the blueboard.  See the attached image.




Amanda_931

Might be OK.  

People do close in the area under their houses around here, sometimes.  

Might talk to you insurance agent about rates on post/pier type construction, though.  

Three years ago they didn't like them here.  But places subject to storm surge are probably heavily penalized for not using that.  And John points out that what the insurance companies hate is a type of building not done any more.

PEG688

#3
Doug your plan would seem to do the job . I might suggest using Hardi board 1/2" instead of the green / blue brd. All ready concrete color as well. Some type of kicker or brace back to something solid inside or triangular bracing might be a good idea as well so the earth wouldn't be able to , over time, push the wall in and under . You'd have to back fill carefully , no big rocks rolling into the wall.

If  the wall needed to be higher than say  4' it would need some addition support/bracing I would think.


Edited to add I see your blue brd is insulation brd, I'd put it on the inside of the studs , put the Hardi outside , the cavity would act as a dead air / thermal break in a way.
When in doubt , build it stout with something you know about .

John Raabe

#4
Doug:

I think you have a pretty good system there! :D You should use PT framing and, to get ALL the benefits of a continuous foundation, you could build in more racking resistance (for earthquake or high wind areas) by sheathing the frames and posts w/ PT plywood and then adding the foamboard and stucco to the outside of this shear wall. This would be as airtight and better insulated than a standard concrete crawlspace foundation (It would also be much less likely to get kicked in than the the foam/stucco wall.)

If you don't need the racking resistance then the cement board PEG suggests would be a good option - especially in areas where higher insulation is not needed.

Good suggestion. This is a valuable thread for an upgraded P&P foundation.

PS - In hot climates like Texas you may have some advantage of earth cooling if you do an insulated foundation and then provide good air circulation into and out of the crawlspace. I know that is all the cooling needed here in the NW - my insulated plenum is great in the summer. This option would depend on your seasonal soil temperature.
None of us are as smart as all of us.


Doug Martin

Cool! We have a discussion this time.  ;D

Thinking more about it the "system" does need to be more sturdy.  How about something like this:

Instead of conventional 16" OC 2x4 the barrier wall could be framed with vertical elements at 45 degrees to form a series of triangles to resist racking of the posts.  Then with the blueboard mounted on the inside, as suggested to create an air space for added insulation, cement board (the 5x3 sheets they sell to line tub walls when tiling) could be screwed on the outside of the wall and then fiber cement could be stuccoed onto the outside.  The wall would then be buried as shown before in a gravel trench.

desdawg

This is how I am skirting my mobile home up north. The concrete pads are septic tank lids that I had to remove when I needed to add rings and round covers to get them closer to the surface. I drilled an expansion bolt and used a post base, then cut a treated 4X4 to fit. I have a supply of treated 4X4 short length's on hand that I picked up somewhere.  I will put another concrete pad midspan and frame a treated 2X4 wall to fit from top of concrete to the bottom of the rim joist. I will continue the masonite siding down the knee wall and backfill under the wall. Concrete is really pricey up there so I decided to use what I had. I call it post and beam skirting for lack of a better name.  :)
I have done so much with so little for so long that today I can do almost anything with absolutely nothing.

John Raabe

#7
Doug - You angled braces with mill board will provide more racking resistance then vertical framing, though probably not as much as vertical framing and plywood.

Desdawg - Sounds good, but I'd check that Masonite siding and see how it performs close to the soil. In my wet climate earlier Masonite siding products have been a disaster with the material absorbing water and leading to mold problems. There is a class action lawsuit you can read about here - http://www.residentialinspector.com/issues.htm#Masonite%20Siding
None of us are as smart as all of us.

desdawg

Thanks John, I hadn't thought about mold. I know termites don't care for masonite and that was what I was mainly concerned with as they are ferocious in this part of the world. I guess the litlle buggers aren't glue sniffers.
I have done so much with so little for so long that today I can do almost anything with absolutely nothing.


desdawg

The saga continues. My bending, stooping and framing muscles haven't been exercised in quite some time I can tell you for sure. The home is 14' X 70' so I did get them limbered up after awhile.  :-/
I have done so much with so little for so long that today I can do almost anything with absolutely nothing.

desdawg

After much crawling around beneath the house getting the plumbing insulated and creating some low point drains for the water system I finally got some skirting on. I wound up using a clad OSB rather than masonite. The bottom will be painted with a borate paint for termite protection. Two coats of that and the finish paint can go over it. I will be replacing all of the window trim and installing bats over the siding sheet joints. And I will be using a piece of  8" horizontal lap siding over the joint where house meets skirting. Paint will be the same color as my land sea container with a chocolate brown trim.


glenn-k

Looks like shes coming along, desdawg.  

I went to a house yesterday where the lady was renting and the owner told her she could paint the house an earth tone color.  As luck would have it, Lupines were in bloom so she painted it all purple - yup - garage and all -- like the old Dodge color -- Plum Crazy. :)  

desdawg

That color will save a lot on the old electric bill. No outside lighting. Glows in the dark.  ;)