reinforcing existing foumdation

[njpls]

we are repairing an existing porch with roof on 80 year old house. it has a masonry foundation, however no footing. the foundation is +/- 3' below grade and extends 2.5' above grade. it is obvious that the foundation is sagging which is causing the problems. the existing foundation is to remain due to costs to remove/rebuild. we are looking to shore up the foundation at the corners and under each porch post. what is the most effective way to do this?

 

[kslee1000]

Wood post? How it was supported, on floor with brick pedestal below? Size? Is the porch enclosed? by what? What is the usage of the roofed porch if enclosed? What type of soil? Need more details.

 

[vandede427]

helical anchors.

 

[Den32]

yes, agree with vandede427, use screw piles (helical anchors)

 

[BAretired]

I think the job is a bit tricky. You cannot support the masonry wall without undermining it and running the risk of causing further settlement or even worse, collapse.

I think the best method is to support the roof of the porch first. This can be done with timbers angling slightly over to wood plates on grade. When you are satisfied that the roof is adequately supported, it should be safe to carefully underpin the masonry wall in sections.



BA

 

[JrStructuralEng]

I agree with BA, i think your best option here is to shore the structure and underpin. I have done something similar.

It may be difficult to install helical piles, especially if these are unreinforced masonry walls.

 

[MiketheEngineer]

Or just let it sag and cut new posts to fit??

However - Might still continue to move...

 

[oxbridge]

i'd go with the helical piles. saves on excavating and having to remove soil-alot cleaner job. but will depend on the size of porch etc as the walls made need strengthening to span between piles. can be done using bed joint reinforcement epoxied into the moatar joints

 

[BAretired]

I don't know how helical piles can be installed under a wall. They can be installed outside the wall but not inside the wall, so it is not possible to use needle beams.

Please, all you advocates of helical piles advise how they can be installed where required?

BA

 

[msquared48]

I'd look as to why the wall is "sagging" and try to alleviate the cause prior to making any leveling corrections.

It could be a downspout that is releasing water too close toi the wall causing settlement. If this is the case, the downspout disgharge needs to be directed further away from the building or tightlined.

Mike McCann
MMC Engineering

 

[lrhg]

Do you know the condition of the masonry wall below grade due to the settlment? seems that that if the settlement is noticable on the porch, there might be sufficient movement to have caused cracking of the masonry foundation wall as well... just a thought.