Reinforce existing cinder block foundation

5 years ago

We recent retired to a 1950’s ranch cottage with cinderblock foundation. (Although there is a full basement which was added/dug out afterwards) I am trying to figure how we can create loft space in the attic...will need to raise the low roof and create access, so lots to figure. However, my husband is concerned that the cinderblock walls may not support any additional weight. The blocks were not filled in. Is there any way to fill them or add supports to give the foundation extra support? Lolly columns are supposed to be temporary, but maybe someone can give me some advice as to who to turn to. Other options? I want to raise the roof about 3 feet.

Thank you

Featured Answer

3onthetree

5 years ago

If it was a crawlspace with true pre-1960s "cinder" block walls (as opposed to "concrete" masonry units), then they are probably in disrepair (lime content and limey mortar) both the blocks and mortar joints, as crawlspaces (and that era in general) were not damp/waterproofed outside. Then it was underpinned later for a basement with a deeper stem wall, with concrete footings and unstated wall type (concrete, cinder, or CMU?). As your husband should know, basement walls act as retaining walls against the soil pressures inward, so grout filling and rebar/ties (both vertical and horizontal) are part of the structural system. Your original crawlspace walls would undoubtedly have had none. That may not affect a 2nd floor though.

There are different types of lally columns. Some are temporary, some are designed to be permanent, and the latter are just considered columns/posts. They would typically be located for central beam support, not in the perimeter walls. If adding a 2nd floor, the beams, columns, and footings for those columns would need verified.

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Comments (7)

User
5 years ago
Sounds like a teardown and rebuild. A bad foundation and popping the top to add a habitable second floor are two very very expensive projects. You only want to spend as much as the house costs. Or more.

Or move to the house that is already how you want it to be.
L Langlois thanked User
PRO
Joseph Corlett, LLC
5 years ago
You could build a skyscraper on those hollow cinder blocks. Have your husband worry about something he may know something about please.
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L Langlois
Original Author
5 years ago
Thank you both for taking time to answer. This reply is also to Hughey.

Thank you, Mr. Corlett, for assuring me that our foundation should be sound! I appreciate that. I should also have mentioned that the original cinderblock foundation sits on a concrete foundation, poured several years after, when they decided to dig out/add a full basement. They didnt want to disturb the original foundation walls.

Our home, which we just moved into fulltime, is actually in impecable condition. So, no tear down or buying another home. The cinderblock foundation is certainly adaquet for the existing structure. We have had several architects and contractors complement how well it was built. We do not consider raising our roof a couple feet to access the attic, adding a habital second floor. It will be a loft...for light storage. (maybe yoga?) I dont want nor need more rooms to clean.

As far as my husband is concerned, he just wants to be sure everything is done by the book. He has always been an strict enforcer to protect structural integrety and safety as an active member of the International Code Council for over 35 years. I’m just trying to do my own research so i can educate myself. That’s what I did before i retired: Research.

Thank you again for your comments.
PRO
User
5 years ago
Bumping up a roof to add a loft is 90% of the work of adding a second floor. It costs a huge amount, and has no payback. Adding a second floor has a lot more payback, with very little cost increase.

It’s pretty doubtful that an old unfilled actual cinder block foundation can support either project though. It may not be doing a good job supporting a single floor.
L Langlois thanked User
worthy
5 years ago
Invest in a structural engineer's inspection and written conclusions about the foundation's capacity to support added weight.
L Langlois thanked worthy
L Langlois
Original Author
5 years ago
last modified: 5 years ago
I am sorry for the delay in my reply…we had family from out of state visiting. However, i greatly appreciate all the ideas and information you all have given me!

3onthetree, you have definitely given me great information to refer to, as well as Worthy’s suggestion of getting a structural engineer report to answer any doubts, once and for all.

I understand creating a loft may not give us the return a full second floor with designated rooms might aford, however, not only would our septic (someday city sewers?) not have the capacity for additional bedrooms, I’m also thinking of my own needs. Addtional rooms are actually what I dont want. But thank you for the suggestion. Our children who are in support of our idea of a loft, will eventually inherit this beach house.

Again, thank you all for taking time out of your day to respond to my inquiry. I will be referring back to your answers, as well as sharing it with my husband, as we (hopefully now) look towards planning our project.