Author Topic: Timber frame barn footer/foundation/sill restoration (Read 2915 times)

blackhecilopters · « **on:** April 19, 2016, 10:54:29 AM »

Hello all! Brand new member. Just started poking around the stickies and threads. Anyways, in 2013 I purchased an 1830s home in Galway, upstate NY. The property included a 3 bay timber frame barn. Guessing post Civil War? Beams are not hand hewn, believe they were done by a saw. The frame of the barn is in pretty good shape except for the footers/sill. The original sill is gone and was retrofitted at some point by a concrete sill that has since rolled from frost and has now been removed. The barn is currently sitting on an assortment of posts/cribbing/lally columns.

I am looking for advice and guidance regarding how to redo the foundation. Currently, I am planning on digging 4' holes and pouring concrete in to create a 'pier' much like a pole barn but without having the post in the ground. I was then thinking of connecting each pier with pressure treated 2x8s stacked between each 'pier' to form a sill. To me this sounds like a sort of timber frame/pole barn hybrid. After I have the barn level and sitting on good footings I was to pour something like an Alaskan slab.

How does this sound to you guys? I can add some pictures and provide any that may be useful in guiding me on my new adventure here. Look forward to any and all advice and guidance you guys can provide!

Thanks,

James

edit: adding links to some pics

Jim_Rogers · « **Reply #1 on:** April 19, 2016, 11:42:21 AM »

To understand the correct size of the barn and its footings you need to measure the barn accurately.
When we do this we measure it at the plate where the rafters sit, gable end to end. And at the tie beam from wall to wall.
These two dimensions, whatever they are, will be the basis for your foundation size.
It maybe an odd number and not land on a even foot mark.

One barn we measured was 32' 4" x 23' 8". So again it may not be something that makes sense to you now.

Once you have these two dimensions you'll know how far out the bottom of the posts are and you can work towards moving them back into position to stand plumb.

One of the reason's why things like what has happened to you is that the barn is sitting very low to the ground.
Some old barn actually sat on the ground or on large flat rocks in the corners.
To prevent you barn from rotting out again, you need to do one of two things.
Either raise the barn up or dig out around it and get some distance between the finish grade and the first piece of wood.
Create a way for rain water to "run off" instead of wetting the barn timbers, siding and foundation.
There are methods to putting in replacement posts parts that will make those rotten posts strong again, and most are not that difficult to do even in a standing barn.
Good luck with your project, and keep asking questions.

Jim Rogers

blackhecilopters · « **Reply #2 on:** April 19, 2016, 11:57:50 AM »

Jim, good point about the measurements. I need to get a baseline on getting this thing back to square.

I saw this image in one of your posts which looks like an acceptable solution for a footing, but I may elect to not have any wood to ground exposure. Maybe something like a sonotube full of concrete to a few inches above grade. Possibly add a wet set bracket??

Jim_Rogers · « **Reply #3 on:** April 19, 2016, 01:10:55 PM »

As an older building, it most likely doesn't meet code. Or is required to meet code. But in my area code says that there should be 8" between finished grade and the first piece of wood. Whether it be pressure treated or not.
That would be a good goal if you intend to raise your barn up to straighten it.

I noticed that you do have some cribbing holding up some beams.
The company near me that does a lot of restorations uses 6x7 cribbing. The stack them 7" tall. Then when they need to slide three or four in to place the jack on the roll them over to make them 6" tall. That way they can slide them in and out easily.

I would caution you to not leave your barn being supported by hydraulic jacks for very long. Should the jack fail the barn could settle down and some times that can be a bad thing.

Also, straightening a barn may take some time. What I mean is you may need to jack it up a little and then wait a day or two and then jack it up again. It settled down over years and pushing it right back up all in one day may not be the best solution. Pushing it up a little at a time and letting it get straight may go easier.

Also, I have a bracket design that we used to hold up a post from the side while we fixed a rotten bottom.
My local welding shop made it up for me for $40. You could get some made up for you and that way you can hold up your posts while you work on them.

Jim Rogers

PS. If you'd like a copy of the drawing, send some money to support the forestry forum and I'll give you a copy. $1 or $5 whatever you can.

Magicman · « **Reply #4 on:** April 20, 2016, 09:48:59 PM »

Welcome to the Forestry Forum, blackhecilopters. I commend you for doing your homework and learning the FF basics.

ljohnsaw · « **Reply #5 on:** April 20, 2016, 10:15:52 PM »

I want to commend you for wanting to do the right thing. Too many people would take the easy way out and just demolish it and build something new. Best of luck in your adventure!

blackhecilopters · « **Reply #6 on:** April 21, 2016, 08:47:29 AM »

Thanks for the tips and kind words everyone. It is definitely an adventure. I've always been mechanical but am learning new things on the building side of things being a recent homeowner. I work with computers all day so it's nice to have something non-digital to work on!

Here are some pics of the ideas for a pier to post system I think I will try to use. This Simpson knife blade post base looks promising.

cast that into my pier or at least 2 rods and attach my new repair piece to it.

What do you guys think? Still just bouncing ideas around...

Jim_Rogers · « **Reply #7 on:** April 21, 2016, 10:58:09 AM »

What we did:

I have written a step by step guide of how to cut a bladed scarf joint in a timber, including how to do it in a post, hanging in an existing barn.

You can use a half-lap as well, as long as both surfaces are fully bearing the weight.

Jim Rogers

blackhecilopters · « **Reply #8 on:** April 21, 2016, 03:46:06 PM »

How can I get a look at your guide? Those joints are impressive, much beyond my level (beginner).

Jim_Rogers · « **Reply #9 on:** April 21, 2016, 11:46:50 PM »

Quote from: blackhecilopters on April 21, 2016, 03:46:06 PM

How can I get a look at your guide? Those joints are impressive, much beyond my level (beginner).

Go to: http://www.forestryforum.com/board/index.php/topic,50674.0.html look for item #M326**

Jim Rogers

VictorH · « **Reply #10 on:** April 23, 2016, 05:35:04 PM »

I'm also a beginner - take your time and you can cut those joints that Jim showed. I believe they will serve you much better than simple lap joints.

Victor

S.Hyland · « **Reply #11 on:** April 24, 2016, 10:29:06 AM »

I'll second VictorH! The most complicated joints are not really complicated when broken down mentally. If one can cut an accurate half lap, one can cut the scarfs that Jim pictured. The same rules apply, just rearranged and repeated!

Brad_bb · « **Reply #12 on:** April 25, 2016, 01:43:34 AM »

If it were me, once I'd measured the frame, I'd seek foundation design help from a proper engineer with timber frame experience. They need to determine the footing size/area for the projected weight of your barn. This will be based on building weight, live floor loads, snow loading, and a soil test. It also needs to be determined how deep the footers need to be to reach undisturbed soil. As others have mentioned, it needs to be determined at what elevation the floor of barn needs to be for proper grading.

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