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JLeslie's avatar

Can you increase the height of the side walls and ceiling on an old Cement Block or wood frame home?

Asked by JLeslie (64650points) 1 month ago

Cement block construction (CBS). Can you just remove the roof and add more block to the outer walls and replace the roof? I have seen renovations where second floors were added to houses, I don’t know if they were CBS or wood frame. Adding ceiling height, I would think all the plumbing can remain the same, so there is not that issue, except for air ducts and maybe the gas line if that is in the attic, but not the water lines. Also, I am assuming (bad to assume) that there would not be a need for support walls like when a second floor is added.

Thanks for any knowledge you have in this area.

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5 Answers

gorillapaws's avatar

Major disclaimer that I’m neither a builder nor an engineer, so take this with a big grain of salt.

It’s a great question. The one point I feel confident in contributing is that in engineering they talk about compressive strength (squeezing) and tensile strength (stretching). Lumber does well under tension and less so under compression (it buckles and splinters), whereas masonry does well under compression and poorly under tension.

This could mean that in a wood frame house, additional reinforcements to the existing wall might be necessary to support the additional load above it, Whereas running additional courses of mansonry wouldn’t require any additional structural reinforcement. Then again a taller wall may receive significantly more horizontal wind forces during storms and so there could be more factors in play. I’m curious to see what more knowledgable people have to say about it.

Entropy's avatar

x2 on @gorillapaws ‘s disclaimer. You should talk to an engineer or GC about this.

What I’ll add to what @gorillapaws said is that there is a limit to how high you can go depending on the DESIGN of what’s below it, how WELL it was built, and by material. There’s a good reason ancient buildings never went above a certain height because their materials and designs could only go so high.

I’m presuming your cement blocks have rebar and such to help out, but there will be a limit to how high you can go. If the structure below was only designed for a certain high, you may not even get that high.

If you tore the roof off, and were looking to ADD blocks, I should think you’d want to have some kind of rebar cemented in and linking the blocks together. When cement foundations and retaining walls are built, I see bits of rebar and cement inside the gaps being used to lock them together. Your new level would need a way to lock into the established bit below it. And with everything already being dried and cured…how would they accomplish that?

But, I’m not an engineer or mason. Maybe they have techniques and it’s easy. That’s why you shouldn’t lean on an anonymous internet forum for stuff like this. :)

JLeslie's avatar

I am 99% sure newer CBS structures do have rebar. It is why I think it is easy to convert a window into a door (usually) when adding an addition, but not easy to cut out a new window or door, because I guess you have to worry where the rebar is. Old houses that are CBS and only 8ft side walls, I have no idea if they have rebar, or maybe less rebar.

SnipSnip's avatar

If you have enough money, you can get pretty much anything you want done to your house.

Dig_Dug's avatar

Your structure would have to be sound, plumb and level, no rot or deterioration and the foundation would need to be strong and secure. An architect and inspectors would go over the structure and draw up plans to conform to current codes and materials and everything would need to conform to the setback and site evaluations of the property, lay of the land and surrounding lots easements etc. But sure as long as everything is kosher and you have the funds, I see nothing wrong with expanding your home if this is something you are wanting to do. I just may have a little knowledge in this area.

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