looking for advice on what kind of wood to jack up a house seeing that sometimes conventialwood sometimes can,t handle the stress , someone told me to use hemlock seeing that the tolerences are much higher , we think we have to raise the building up around 4 to 6 inches , the type of house it is a post and beam one room school house , i would like to post pictures but i don,t know ho to on this sight any insight ,
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Your description of what you are asking is too vague. Are you asking what to use as a post for jacking or what to use under the house after it is jacked up.
"Conventional wood" what is that? Go to the Western Wood Products Association web site. There you should find tables that will give you the relative strength of different softwood species. On the tables, you will see an SPF category, this is where your Hemlock Fir will fall. You will notice that Douglas Fir in the Fir/Larch category is stronger.
However, with post and beam construction, and the associated point loads on the posts, you should consult an engineer for advise about adequately supporting the loads. As important as the load bearing capacity (crush resistance) of the wood used, is the attachment to the structure above, the foundation below, and the resistance to the lateral stresses on the building.
Edited 2/28/2008 7:01 pm ET by woodroe
Sounds like you might have a lot of weight to deal with. Consider LVL'S and PSL’S. Better to overrate then underrate. You might what to consult a structural engineer.
Double for IBI's idea
hmmmm, your post perplexs me
if you're talking about cribbing....any wood will do
if it's post & beam, i assume it has a beam floor that you're jacking
is the floor system still good , but just needs jacking ?
if so, jack it to level, crib it, and install new post supports from masonry or pt posts on footings
"if you're talking about cribbing....any wood will do" FWIW The house movers (3rd generation)I know won't use oak cribbing at all. They use DF or Hem/Fir. Their reason is that oak, despite it's superior strength, doesn't "sound off" when over stressed and therefore they have no warning of any impending problems. The firs will make noise and literally tell you when they are approaching failure according to my house movers.
They can't get your Goat if you don't tell them where it is hidden.
mebbe...... i wonder if it's just that they'd rather hump fir baulks instead of oak baulks
i tnink most permanent cribbing is evolving to syp PT around here
fir PT out west..... no rot loss
if it's cribbing , we're really talking about compressive strengthMike Smith Rhode Island : Design / Build / Repair / Restore
Without seeing what you are attempting to do I will offer two solutions.First is to use yellow pine,does not have to be pressure treated.Another post mentioned do not use oak, he is correct oak is much stronger but snaps without appreciable bending.Yellow pine does the opposite,bends a lot before it snaps.You can see if you are overloading with yellow pine.This is the reason wooden gin poles are exclusively yellow pine.
Having said that, you could use any wood that is sound that you get free, including oak.If the load is not great and the cribbing is done correctly.
You do not give the dimensions of the schoolhouse, I imagine it is just a large room with a roof,not a lot of weight.The old post and beam structures I have worked on have a heavy timber for a sill 8x8" is common.If the cribbing height is less than 5 feet to the underside of the beam then solid concrete blocks can be used for cribbing with a piece of plank on top. You need the cribbing at each corner and at intervals in between.If you only have to jack 4 to 6" this should be doable for amature riggers.
mike
Edited 2/28/2008 11:10 pm ET by mike4244
Below is a link to a summary of different posts discussing how to post pictures on Breaktime and using the
Irfanview download which many here find helpful.
24441.75
Cheers
Peach full,
easy feelin'.