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Replacing rotted floor beams in Post and Beam

Hitlist's picture

Hi,

New here and love forum and mag.

I just bought an old camp which it turns out seems to have been an old school house built in 1800's from what I gathered in research. The floor beams which are all old logs squared on two sides are rotted beyond repair.These seem to be only holding up the floor.They rest on a cement wall around the perimeter of camp with a crawl space.The sill beams are notched to give room for the floor beams and it looks like the post are resting on the sill beams also.Being more of a metal worker I am not sure about this repair.Is it really possible that the floor is the only actual weight on these beams?If so it seems like over kill to have such large beams under it (approx 8x8). What is a good method for replacing these and should I use the same type lumber or go with some 2x lumber with tighter spacing?

The sill beams need to be replaced also I would think since being under there and doing the rest it would make sense to fix the whole perimeter.

I would appreciate any of your expert opinions as I see some here do this sort of thing all the time.

 

Thanks

Alan

Are you planning to remove (post #192431, reply #1 of 8)

Are you planning to remove the floor?  Or do you want to do something that can be done in the crawl, without removing the floor?

It would help to have some rough idea of the dimensions of this structure, and the presence/absence of any interior walls or other objects.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Not planning to remove (post #192431, reply #2 of 8)

Not planning to remove floor,sorry.

All work must be done in crawl space of  maybe 3-4 feet in spots

.Some of it must be dug out to give that much room

.It has dimensions of approximately 18 x30 inside with only one room.

No walls inside except very small bathroom that was installed by someone.These would be 5 feet long maybe.

The original subfloor looks like 1x6 pine or spruce and is in fair shape throughout most of camp except under bathroom where there was slow water leak and rotted through.

The original floor is hardwood of some sort about 2 inches thick.Someone covered this in chip board or OSB like a bonehead.When I fix the joists I want to tear out OSB and mabe fill nail holes with contrasting wood like matchsticks or something unless I get a better idea by then.


The only way right now to get lumber underneath is through a 18x12 vent hole so it would be easier to use 2x lumber but if the building need the heavier timbers then they will go in.

 

Thanks for reply

Well, in that space, assuming (post #192431, reply #3 of 8)

Well, in that space, assuming the joists run the short dimenison, you'd need 15-20 2x joists.  If you used 10-footers and crossed on a beam at the middle I think 2x6 would suffice, but that's just a guess, and it may be that code wants 2x8.  Probably what you'd want to do is work two 2x joists in between each beam, then either leave the beams in place or cut them out somehow.

The joists would have to be braced somehow.  Blocking or diagonal bracing between two adjacent joists (where the beam wasn't in the way) would be a start, but you'd probably want more.

A little bit of a trick to figure out how to do the center beam -- probably use several pillars and temporarily use short beams, then fit in the "real" ones near the end.

You have to figure out how to anchor the joists on the outside end.  If the rim beam isn't sound that's a whole separate can of worms.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

I really appreciate your (post #192431, reply #4 of 8)

I really appreciate your quick responses.

I think that is what I will do then.I was not looking forward to lugging big beams let alone the cost around here.

I will need to see how bad the sill beams are and maybe replace them after making sure I can stabilise the walls one at a time.

I will probably want to use large beams for this to keep it the same as original for structural purposes.

Any ides on doing this would help also.

Thanks Again

Replacing the rim in place (post #192431, reply #5 of 8)

Replacing the rim in place could be a challenge.  You might want to seriously entertain the idea of hiring a house mover to lift the whole thing, replace rim and floor, and set it back down.  No idea how much it would cost, but it would be the most direct way to address your issues.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Where would the challenge be (post #192431, reply #6 of 8)

Where would the challenge be if I contracted it out? I will look into it though .

 

Thanx

The sill beams seem solid so (post #192431, reply #7 of 8)

The sill beams seem solid so far.

I have been digging out the crawl space to make it easier to work under there in a few tight spots.

Question on venting.

Should crawl spaces be vented on two or more sides or does this cause condensation under there?

Don't want new joist to rot for a while.

Also not sure if I should open up ceiling to have a loft or at least show beams.Need to get rid of shavings that are there for insulation.

 

Thank You

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Having ventilation on (more (post #192431, reply #8 of 8)

Having ventilation on (more or less) opposite sides will reduce humidity down there -- won't cause condensation.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville