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-   -   How do I jack to replace floor beam on piers in a cottage. (http://www.diychatroom.com/f19/how-do-i-jack-replace-floor-beam-piers-cottage-158215/)

SteveValeriotte 09-27-2012 10:26 PM

How do I jack to replace floor beam on piers in a cottage.
 
1 Attachment(s)
I have a 24'X 24' 1.5 story cottage which has three sistered beams running from front to back and sitting on concrete block piers. Each beam is made up of three sistered 2X12s spiked together. Unfortunately the front end of the centre beam has started to rot at the front end as it is exposed to the weather. I will likely need to replace one of the sisters from where it sits under the front pier, to back a few feet. It looks like the rotted sister is only 6 feet long anyway. The question is, where should I place the house jacks to raise the centre beam off the pier enough to allow me to replace the sister? Only under the beam itself or should I try to raise the joists which sit on the beam too? The photo is of the beam in question but doesn't show the exposed end.

epson 09-27-2012 11:18 PM

Get some ideas: http://www.youtube.com/watch?v=ksnXfM47lPw

allthumbsdiy 09-28-2012 07:57 AM

How bad is the rot? If it is only few feet, I would not think that would have any significant impact to your overall structure.

Since you really don't have a lot of working space under there, you may want to consider chiseling out the rot, seal and then cap the end.

Good luck

hand drive 09-28-2012 08:37 AM

Quote:

Originally Posted by SteveValeriotte (Post 1018893)
I have a 24'X 24' 1.5 story cottage which has three sistered beams running from front to back and sitting on concrete block piers. Each beam is made up of three sistered 2X12s spiked together. Unfortunately the front end of the centre beam has started to rot at the front end as it is exposed to the weather. I will likely need to replace one of the sisters from where it sits under the front pier, to back a few feet. It looks like the rotted sister is only 6 feet long anyway. The question is, where should I place the house jacks to raise the centre beam off the pier enough to allow me to replace the sister? Only under the beam itself or should I try to raise the joists which sit on the beam too? The photo is of the beam in question but doesn't show the exposed end.


Ideally, to replace any part of the girder beam you will need temporary walls built that is located to either side of the beam and holding up the floor system for each room. doing this will allow you to dismantle and repair some of the beam without the floor loads being supported fully by the beam.

SteveValeriotte 09-28-2012 05:15 PM

Beam Condition
 
Thanks very much for the advice. The rot appears to only be about a foot or two in from the end and only on one of the sisters. The other two sisters, however show signs of crushing as they have settled/sunk down onto the concrete piers an inch or so. I have about 3 feet or so of space below the beam to the ground at the front of the cottage where the rot is.

Do you think a single column of concrete cinder blocks is strong enough to adequately support this structure? As you can see in the picture, that is all they have for piers. In the front it is 3 or 4 feet high.I just wonder if that is an adequate pier. I think there are only 3 piers under the 24 foot structure supporting the 12X6 beams.

mae-ling 09-28-2012 05:57 PM

In regards to whether or not it is enough support. Has it shifted/sagged? If not it is enough.

To fix your existing beam. Block up the beam only supporting the 2 good ply's, add an extra couple of supports in the middle. (there is 3 supports now? One at each end and one in the middle?)
Remove the damaged ply, put a new ply in, remove temporary supports.

It looks like the beams are just sitting on the blocks? That edge will cut into the beam. really need something flat for it to sit on, like a steel plate or something on top of the supports. Have they all cut in or just the rotted/wet ones?

It looks like the blocks are on a large rock?

Please answer all questions for the best answers

SteveValeriotte 09-28-2012 06:11 PM

Sagged
 
I think it has sagged about an inch or so where the rot is. The doors in the bedrooms upstairs will not swing, so I also suspect sagging. There is no evidence that the building has shifted in its 30 odd years of existence. Thanks for the tip about the steel plates. I will put some in place.

Yes, there are only three supports/piers under the 24' beam now. Are you suggesting I add a couple of more temporary supports or permanent supports?

The concrete piers go below the soil but I do not think they are sitting on a rock. They may have been dug down to the underlying bedrock and are hopefully sitting on that.

It looks like only the wet ones have cut in.

Thanks again!

mae-ling 09-28-2012 06:19 PM

The added supports are only temporary sitting on the ground. Because you are removing 1 ply of the beam as you work on it. it will be much weaker and needs additional support. Have the new ply ready to go in so that it is not out for long. I don't just set it in place but fasten it with screws and scab 2x4 or whatever so it can not shift.

Also make sure you cover the ends of all the beams so this does not happen again.
Also also - Jack it back up into place where it should be. I lift no more then 1/4 inch per day once the jacking gets tight.

SteveValeriotte 09-28-2012 06:45 PM

Another Photo
 
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Thanks! I have a better idea of what to do now. Here is a photo showing the front of one of the other beams that is not rotted. What would you cover the exposed ends with...metal flashing?

mae-ling 09-28-2012 06:49 PM

I'd cover it with the peel and stick rubber flashing used around windows often, then cover that with metal

SteveValeriotte 09-28-2012 07:17 PM

Rubber Flashing
 
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Very interesting! I hadn't thought of that. Here's another photo of the other beam under the cottage. Not in too bad of shape, I hope! I am just taking possession of this cottage on Oct 1.

mae-ling 09-28-2012 07:20 PM

Looks like it might be treated lumber?, which is what it should be.
Use treated (PWF) for your replacement.

SteveValeriotte 09-28-2012 07:50 PM

Pressure treated
 
Yes, this one looks pressure treated but the others don't...interesting. I'll definitely replace with pressure treated wood.

allthumbsdiy 09-28-2012 08:21 PM

btw steve, that outlet box does not look like it is outdoor rated.

Though you kinda have a drip loop, water can still get in, especially with those holes.

Good luck

SteveValeriotte 09-28-2012 09:10 PM

Electrical
 
Thanks, AllThumbs, It looks like the electrical is going to need a little work too!


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