Pros and Cons of Slab/Post n' Pier

[Les C]

If ground termites are an issue at your location and if you are okay with using the chemistry used to treat their infestation, P&P allows for easier treatments. BTW, cement slabs are not a barrier to ground termites; they can bore through it to get to the wood.

If you go with slab, there is an option for plumbing that may be better than copper, Aquapex tubing
http://www.wirsbo.ca/default.php?id=32
It's used for propane and water. It supposedly lasts longer than copper, too. But, like any pipe embedded in cement, if something does go wrong with it, you still have to break up the cement to get to it. It's not only for use in slab foundations.

Les

[toucano]

Chili - you might as well flip a coin. Both have advantages/disadvantages that have been thoughtfully presented by others here. Personally I like P&P, but I could see sites and/or structures where concrete would be just as good an option. WELL constructed is the key to being happy with whatever you choose. If I was going with concrete, I would be very picky about who I had do my slab. If Catherine D's (Cat) SO was available to do it, I would choose him because I know he does 1st class work.

[mella l]

If ground termites can bore thru concrete, do they live in lava also, or do they need soil? If they do not live in lava rock then perhaps slab might be the way to go? Any thoughts on this would be appreciated. Mahalo

mella l

[Chili]

Carey, After the tree removal and "leveling" of the lot, I think there's going to be a 2' drop from the front to back of property. There's a good chance it will be a combination of concret slab and post and pier. I couldn't agree more that no matter what is used, the most important thing is good construction.

Les C, my contractor is obligated to perform ground treatment for termites prior to the start of construction. By the way, interesting web site, thanks.

Toucano, my house is being built thru the USDA rural farm program. Because it's a government loan there are a lot of " Big Brother" clauses that must be adhered to. All licensed contractors and all sub-contractors must have a license. Honsador is bonding the job and there will be regular inspections by a government representative, to ensure all work is performed up to regulations. Since I don't know that much about construction, it's going to be a learning process for me as it goes along.
I can't thank all of the folks who have supplied numerous tips and ideas enough. Everyones opinions have been noted and they all will give me lots to think about. Mahalo again to all.
Chili

[Les C]

Chili, you should be aware that a treatment for ground termites before pouring a slab doesn't guarantee that they can't infest via the ground later. I'm not sure about this but the chemistry may lose its potency over time. Ground termites can act very quickly, forming a large colony.

Les

[Kapohocat]

Good luck Chili! I feel a personal interest since I have watched your project from the intial thought of land purchase with Winston! You are thorough and thoughtful and will do well with the construction whatever the foundation you choose!

[Chili]

I have heard of spikes that are placed in newly poured concrete so that it can be continually treated for termites. I know those little buggers are persistant. I'll check further on that.

Cat, you're right, you've been there from the beginning with Winston, Bless his heart, and yours too. You, and so many of the folks out there are dealing with, or have already dealt with what I'm going to be going through for the next 6 months. I don't know how you do it without losing your sanity.

Once again, I want to thank all of you who shared your thoughts with me.

And I just want to leave you with this:

"I"M MORE CONFUSED THAN EVER".

Only kidding. Thanks again,
Mahalo and Aloha
Chili

[Carey]

Chili, if you are going with slab & wood const (the framing on our slab is aluminum), you may want to investigate the physical barrier University of Hawaii developed using a special sized basalt
http://www2.hawaii.edu/~entomol/pdf_files/hsp-3.pdf
Aloha, Carey

[Royall]

Just before pouring the slab for the garage, we had to have the ground treated for termites. It is required by the county for all slabs and they want to see the receipt for it before the will final the structure. We the man came out to do the work I point blank asked him if this was just a waist of time or not and he told me that the treatment will only last about one and a half to two years. It appears to be just another way to keep people employed here in Hawaii. With that said it is still easier to re-treat under the house on P&P. I have come across two items that are supposed to stop the termites. One was a fine stainless steel mesh and the other was a basalt rock that is crushed to a specific size. I believe the latter was developed at Uof H.

Royall

What goes around comes around!

[Noel M2]

Chili,

I think there are some misconceptions surrounding termites. A common one is that they can eat concrete and even lava rock. If this is causing part of your confusion, allow me to shed some light.

Subterranean termites (the Formosan) are the ones described in earlier posts. There are some parts of the island where they are prevalent, for example, some parts of Hilo like the Sunrise Ridge. They live in the soil where they can build large colonies. Termite stakes that you find at Home Depot or that Terminix installs are generally targeted towards addressing these termites.

While all termites go after cellulose, they can bore through insulation, plaster, and other materials in search of sustenance. They don’t eat concrete and rock. What they can do, however, is find cracks and other vulnerabilities in a structure to find their buffet. If they cannot find a crack, they will extend their ‘tunnels’ above ground – creating protective dirt tunnels up pier blocks and concrete foundations - to their food source.

I’m not certain if the Formosan lives in rocky areas of Puna but with the transfer of soil for landscaping purposes, it is very likely. The fact that some builders and dozer folks bury trees when they clear lots does not help mitigate the risk.

As mentioned in the responses, there are a number of things that can/should be done regardless of your foundation (ground treatment, good construction practices, and vigilance after construction). The last point demands that we regularly inspect around the house, eliminate any ground–to-wood contact, and mitigate any evidence of infestation. Having a contract with a termite control company can also provide peace of mind.

The ultimate mitigation is to remove the meal (build with concrete and steel and other non-wood materials). Of course, this is not always feasible or desirable.

To make matters more interesting…

The Formosan has a distant cousin – the Drywood. This termite is a little more high-tech. It does not dig around in the ground looking for a meal. It flies. The drywood termite will swarm periodically to find new colony-sustaining wood (dead trees, logs, books, furniture, houses). Once they land on a home, they will loose their wings, crawl into cracks and hope they find cellulose. Once a colony is established, you might find evidence of their presence via their droppings (piles of tiny black/brown granules). Spot treatments (insecticides injected into the infested area) or fumigation/tenting for large infestations are generally how we these are killed.

To mitigate this type of infestation, ensure that cracks and crannies are sealed and painted. Use of non-wood siding like HardiPanel/Plank can also help.

So – it can be a double whammy – you’ve got enemies attacking from above and below and unless you completely remove the ‘meal’ – good construction practices, maintenance and vigilance will be an ongoing part of the home ownership journey.

Am I an entomologist? No, I just stayed at a Holiday Inn. ;-)

Best of luck with your project.


Noel

Edited by - Noel M2 on 10/21/2006 11:30:43