Basement construction

kmartin2 · August 8, 2007, 6:46pm

Recently viewed a basement constructed of treated plywood, not poured concrete or concrete block construction. Not aware of this type of basement construction. This home was built outside city limits, no code inspections required except for electrical. Can anyone provide feedback on this type of basement construction? What is the life expectancy of this type of construction? What are the consumer concerns? What should we inspectors be aware of?

Frank_Newman · August 8, 2007, 7:02pm

I’ve seen a few examples of this type of construction here in GA as well, so will be interetsed to hear the answers you get.

clederhaus · August 8, 2007, 7:33pm

I saw this type once when I worked on a volunteer fire department in Dalton WI. We responded to a collapsed home. It was only 3 years old. It did not hold up the frost in the ground. The contractor had too many rocks in the back fill and when the ground froze it pushed them right into the wall. We got to use the home for fire practice the next spring. That was the first foundation we could not save. It was a Menards home. I do not think they have that option here any more.

lkage · August 8, 2007, 8:46pm

We have been building with PT wood basements up here for decades.

They are designed and engineered specifically for your site and, built properly (Which means proper backfill, also.), are dryer than masonry and stay dryer. There are no musty smell and they insulate easily which means cheaper to heat.

More info here:

http://www.toolbase.org/Technology-Inventory/Foundations/wood-foundations

http://www.dulley.com/docs/f666.htm

http://www.frtw.com/cca-pwf.php

http://www.naturalspacesdomes.com/all_about_domes/pages/NSD%20AAD25-26.pdf

Brian_A.MacNeish · August 8, 2007, 10:02pm

I’ve worked on or around about 15 permanent wood foundations (PWF’s) from 1983-87 and the last was 2000. If I don’t go simply to a floating slab on grade for my retirement home, it’ll have a PWF. Done properly as previously mentioned, they outperform concrete for dryness, easier to insulate and are cheaper…even though there is no large volume being built.

Get this- The system works so well, they don’t even need foundation perimeter drain tiles!!!

The last one in 2000 was for one of my former employees who called from another province to hire me to oversee the installation of a PWF under his 112 year old home after he had it raised, removed the partial stone foundation and deepened the hole. It was quite the project -started Sunday AM and was done Sat PM- and we had 18 corners to frame.

I visit this old friend/former employee at least 1-2 times per year now. Since his site was not the best with clay soils and poor drainage, each visit we have a look around and it’s performing well. The oldest one I know of in our area is 30 years old this year. I last visited it about 8 years ago and the original owner said “No problems!” The first in the US was 1938 and still going, from what I know.

Up here, they don’t need to be engineered for most sites as there is a recognized standard from the Canadian Standards Association that is referenced by our building codes. The Canadian Wood Council has a book with illustrations explaining the system and how to meet the standard/codes. see http://www.cwc.ca/

Late edit:
Seems the toolbase.org site does not have their history right: They say the 1960’s were the beginning years but my original readings in the 1980’s said 1938. Just did a quick google and found this:
“Wood foundations originated in 1938, following the development of preservative-treated lumber and plywood designed to resist decay from moisture and infestation from insects. To date, over 300,000 homes in the U.S. have been constructed with wood foundation systems.”

rhinck · August 9, 2007, 12:24pm

Another great resource is the American Plywood Assoc. website. I have personally used these folks and built PWF foundations.

Rick

kmartin2 · August 15, 2007, 7:56pm

Appreciate the information sites. Thank you

rwand1 · August 15, 2007, 8:04pm

I have inspected quite a few over the years.
Most all had some problems mainly water entry in basement.
Not many inspectors are familiar with them.
They should be installed with weeping tiles in my opinion.
They do have a limited life span.
Personally speaking I would not buy one.

rwand1 · August 15, 2007, 8:12pm

National Research Council

http://irc.nrc-cnrc.gc.ca/pubs/cbd/cbd234_e.html

Brian_A.MacNeish · August 15, 2007, 8:41pm

rwand1:

I have inspected quite a few over the years.
Most all had some problems mainly water entry in basement.
That’s quite interesting to me, Raymond. On the ones I’ve worked on or built, only one had a water problem and that involved two stupid human interventions about 7 years after its construction. I was the GC in 1987. We had a soupy clay/sand soil with the wood footing course about 1-1.5’ above a lake water level approx. 100 ’ away. We had installed about 1.5’ of shale to raise the footing level and give the structure a solid base. The first owner, my client, never had a problem in 7 years.

The first mistake by the second owner was to change the sump pump from a pedestal to submersible. At the same time he did not realize that he reset the water level in the pit about 8-9 inches higher to be at the bottom of the concrete slab. The extra 8-9 inches had been a sump forthe storage of ground water in wet periods.

The second mistake involved the new owner of the undeveloped lot next door, an excavation contractor. He was building a new house and wanted to clear all the alders/brush from the rear of his property to have lawn all the way to the lake. It was easier to get to this area through the rear uncleared area of the house I had built. He offerred to clear this property also and would leave all larger trees in place.

(I now live 200 miles away and its 7 years later) The next spring I get a call from the new owner about a bit of water entering around the perimeter of the unfinished basement. I talk to him about changes…he says none. By luck, I was going to the area to work and visit friends in a few weeks. Found the raised water levels in the sump pit and noticed none of the trees in the rear had leaves budding out- the excavation work had raised natural water levels
and killed the trees- the owner now had a couple of cords of standing dead firewood!! NONE OF THIS WAS CAUSED BY THE WOOD FOUNDATION.

Not many inspectors are familiar with them.
Since I’ve been in Halifax, I’ve been called 4-5 times after people had inspections by others who could not give an opinion on what they were seeing!!

They should be installed with weeping tiles in my opinion.
If you really knew how they are built, you may change your opinion, Ray.

They do have a limited life span.
Yes, but every year that goes by proves they are going to exceed the 60 year warranty. Remember, the first was built in 1938- almost 70 years old now. I have a few more stories with positive slants but have to go.

Personally speaking I would not buy one.

No, I might not buy one unless I had confidence in the builder or watched it being built. But isn’t that like any other house?

jsieg · August 15, 2007, 11:58pm

Try this site: www.pwfs.com

Or give me a call. I have taken a class on PWFS Inspection… I have been involved in doing Draw Inspections on one now for a couple of months. For a matter of fact I just got off the phone with one of the leading experts on PWFS a couple of hours ago.

Jason Sieg
(248) 240-7873 Eastern Time Zone
Michigan

PWFS are designed to out last the rest of the home!!!