Already have a thcik concret slab

[jtbodine]

I already have a concrete slab where a block cabin burned years ago at Lake Malone, KY. Can I start a B/P cabin right on the slab. Size is small, only about 18x30.
Jeff in TN

[StressMan79]

Jeff,

There is a lot of discussion in the member's section regarding foundataions. The general consensus is that it is not a good idea to "just build on a slab." This is for several reasons: the slab generally isn't strong enough to take the weight of a log home, the logs are not far enough off of the ground to prevent rewetting from splashed rain, as well as code issues (check out International Residential Code (IRC) at your local library).

In your case, since the slab was used for a previous cabin foundation, perhaps the weight wouldn't be a big issue. You could lay a few courses of cinder block to get the logs away from the "spash zone." These changes may/may not get you past any Code issues. To be absolutely sure, consult a licensed structural engineer with log home experience. I would also highly recommend taking the class--if you learn nothing (which is next to impossible), as a member, you will have access to members only area (I have been careful not to be too technical in the non-members area). You can ask many knowledgeable members anything you want in there, and they are unfettered in their responses.

[DnLHoops]

Another thing to consider when building on the slab is how you going to anchor your first course of logs to the foundation. The class teaches you how to do this and unless there are anchors already placed in to the slab you may run in to some issues with your local building code.

[zato_ichi]

two ideas about your slab

1) build a 3-4 course block wall or solid cement wall around the slab with piers in the center, use j hooks, rebar or all thread to attach bottom course of logs. This would get your logs up off the ground and provide a nice crawl space under the cabin.

2) you could expand the size of your foundation using the suggestion above and then just pier up the rest to make 30x30 or cut a keyway into your existing slab and pour a larger slab right over it (the keyway helps bond the two slabs together making the joint stronger) still use a short wall for your crawl space etc...

[Loghomeguy]

If the old cabin there was built many years ago it is possible there is no reinforcement bar in the slab, if the slab is not deep enough below the frost line it can heave in cold weather.

Remember, each log weighs as much as a stick-frame wall. Unless your slab is 18 inches thick, it is just not a good idea.

I would never use formed concrete bricks or blocks under logs either.

You can learn more in the members section or in the class itself or from your local building department at the county :)

Mikey

[jtbodine]

To all,
Thanks for the replies on my concret slab. It is very thick but I have about decided to build a cabin on piers in front of it and us it as a garage or patio. Michael, what you said about the weight of each log was an eye opener. Either way it will be a fairly small lake cabin 20x20 plus the porch.
Jeff