What type of foundation is best for a Log home?
What type of foundation does my log home need? I get a lot of calls from customers inquiring about cost and type of foundation needed for their log shell. The foundation on a log house can be a huge portion of the cost. The soil conditions and architectural requirements are usually what dictate the foundation type and specifications. When you are "doing it by the book" so to speak, you need to have a geotech report or soil sample done on the build site. These costs can vary depending on where you are located. I have seen it for $1500 all the way to $7500. There are different types of tests and you can opt to bore more than one sample hole. Your foundation engineer will dictate what type of test is needed. The plan that the engineer produces will have all your foundation specifics for your soil conditions. The engineer will also cost between $1500-$5500 (average house 2500-3500 sq ft). After this process is completed then you will have a more exact cost and timeline figure for the construction plan. The foundation plan will be stamped , bonded or insured.
Now that being said, I have had a lot of customers in the past, especially on smaller cabins, who want me to dictate the foundation myself without the direction , cost, or planning from an engineer or geotech company. After forewarning them of the possible but remote repercussions , I will do it in some cases. I have seen so many geo reports, soil samples and engineer reports over the years, that I have a good idea of whats required for worst case scenario soil. If the soil is of good type, I just build to the worst case scenario conditions. You can also get a good idea by looking at slabs and other structures in the area. Take this advise at your own risk. Texas is a wild west when it comes to building regulation (compared to the rest of the country), so make sure you can do this in your own area.
Here is an example of where I installed a non engineered pier and beam on a small cabin. I like pier and beam for several reasons in this case - The climate allows for it in my part of the country- It stays dry and keeps your logs off the ground and away from the drip line- They make your mechanical and electrical 10x's easier (already a challenge with log homes)- They are forgiving when you plan wrong or need to change the floor plan- Its easy to warranty and repair if there is a problem. I recommend a height of at least 24" to give you room to work but I prefer between 36" to 48" on something like this.
My piers were a min of 36" wide at bottom and 36" deep. The concrete in the piers is about 24"to 30" deep. I build rebar mesh baskets in the bottom around pilings. I also drill and hammer pieces of rebar into bottom of piling and let hang out 6". All girders are double 2x12's, joists are on 16" centers. I put (1 1/4") Advantec decking. Advantec decking makes your floor like a tank. I cannot recommend this stuff enough. It is one of the best products on the market. Once the decking is done you are almost ready to lay logs.
With all that said, I do like a good post tension concrete slab or piers under a slab. If its in the budget and the top of slab is at least 24" from ground, I am good with that too. I also like stem walls with a framed sub floor on top. There are a lot of ways to go about it. Building a small hunting log cabin foundation is a different process from building a custom log home foundation. When general contracting your own project, only you will know which way to go. In my personal opinion, I think anything over 3000 sq ft or 300K, I recommend getting an engineer involved. In a lot of cases people are spending their retirement on these vacation spots. You dont want to risk an unmissed detail or not have a stamped and insured plan on an investment that size.
Guild Log and Timber offers all facets of log home repair in Texas. Visit our Restoration page. Subscribe to my blog post for the upcoming blog on all types of log home issues. Guild log and Timber also offers detailed consulting for General Contractors, Real estate agencies, Architects, homeowners and do-it-your-selfers. We can help give some insight on a broad range of in depth issues with existing log home construction problems and the planning of new log homes and historic cabin restoration. Let our two generations, of log home hard knock experience, be an advantage to you. Contact me for pricing and availability.
