Adding room over garage

[Rastogir710]

Hi, I have 4 bedroom detached house with attached single garage. I want to add a room above garage but not sure about the foundation of the garage, if they are deep enough to hold the room.
Our architect have advised, we just have to add 4 pillars with deep footings around the garage and use steel beams to support the structure. According to him this should not be a problem on structural basis.
However, someone else came to see our garage and advised as our garage is single skinned wall which suggest footings are not deep enough and adding pillars( as per my architect) can create problems later on due to contraction and expansion of soil as pillars and garage both are on different foundations. they said, it can result in cracking in the building at later date.
Really confused what is the right way of doing..... If we have to demolish the garage and do the foundations again for garage, I believe it will be really expensive project and in that case, we have to drop the plan.
Please can anyone suggest......
thanks :)

Your getting into structural engineer territory there! Have you elicited the opinion of the local building inspector at the council as yet?.

My gut feel is you might have to knock it down and re do the walls and foundations. And theres fire regs to consider too!

Is adding piers around the existing garage for second story not a structurally sound option??

I would have it costed out as sometimes adding pillars and steel can be more expensive than pulling down and starting again. Just at the very start of a similar project.

Have you got a builder in to quote as yet?, I say this as my Bro in law is one and he hasnt got that good an opinion of the capabilities of most architects!

Chances are he's had to cope with this problem before and will probally know whats best to do!.

We have done this. We had to dig down a trial hole to see how deep the footings were - and building control had to see it too. Ours was ok. And it was a single skin garage. I can't remember exactly what steels went in, but there were pillars involved. You need a structural engineer. Good luck!

You do need a Structural Engineer. It’s not really architect territory to evaluate foundations and loads on walls. Single brick thickness is a worry. We did this but we had breeze blocks as an inner skin. DH is a chartered S Eng so it was easy for us, but you need to investigate very carefully and I just wouldn’t add a separate upper layer. To look good, it should be one building.