Footings for second storey on a bungalow

[Leelou]

Hi all,

 

We are just starting out with the goal of adding a second storey to our newly purchased bungalow. Both neighbours have already gone up a floor and our bungalow has stairs with a dormer in the roof already. We want to take the roof off and build an additional floor but before doing so, need to find out what the existing structure and footings can take. Do we engage a structural engineer, dig some holes and find out before engaging an architect?

 

Thanks

[ToughButterCup]

20 minutes ago, Leelou said:

[...]

Do we engage a structural engineer, (?) 

[...]

 

Yes.

Your neighbours are an obvious starting point. What's (was) their experience: what lessons did they learn? What were their footings like?

[Tyke2]

Hi

I don't think it will save you anything to wait until you have structural details before appointing an architect. If you are wanting to have an architect on board, they may have some local engineers that they have good relationships with already. Also the architect may advise you on other aspects of the building structure they need a structural engineers view on.

So I would get the architect on board first, tell them what you want to do to the building and let them advise on what they need from the engineer. Which will definitely involve digging trial holes to expose the existing foundation.

[MikeSharp01]

9 minutes ago, Tyke2 said:

I don't think it will save you anything to wait until you have structural details before appointing an architect. If you are wanting to have an architect on board, they may have some local engineers that they have good relationships with already. Also the architect may advise you on other aspects of the building structure they need a structural engineers view on

Interesting conundrum in as much as getting the architect aboard is a sound idea but you need time to do that. Before your do have a read of what @caliwag, an architect himself, has to say on that score, get your mind round the constraints you want to put on them and the nature of your solution both of which will affect the choice of architect. So it maybe that getting a survey will add value by giving you time if you see what I mean. On the other hand and as Tyke2 says having an architect aboard has all the advantages of their knowledge but get your ducks lined up in terms of what you think you want - mood boards etc before you appoint. If its the same as the neighbours then probably an architectural technologist is a better bet than a full architect, cheaper and they more do what you want, which is constrained by what you can think of, rather than give more what you need by interpreting your thinking as a design for you.

 

 

[Triassic]

It's well worth speaking to the neighbours regarding their experiences of adding the extra floor, I'd also ask them about foundations, their use of Structural Engineers and Architects, along with the everyday practicalities of the job, what was it like living on a building site etc.

[vivienz]

Have you seen any examples of this type of work locally, apart from your neighbours?  If so, make a note of the address and then have a mooch around on the planning permission part of your council's website.  You can get a vast amount of information from there, including the names of any architects involved.

[Leelou]

Thanks everyone for the prompt advice! To answer a few points, we're not living in the property whilst the build takes place as we knew it's a roof off job and with three children, it's not a great environment to live in. We've met one set of neighbours who are very nice but we didn't want to dive straight in with the building work topic and scare them off. The reason for asking my initial question is that if we find it's not cost effective to improve the footings, we'll just make do with the bungalow and expand on the single floor. Not ideal but more of a "make do" approach and in which case we wouldn't engage an architect.

 

I've also already done some digging on the internet and have found the historic planning applications and the architects the neighbours used. At this stage I'm still unsure, architect or structural engineer first given the above... ?

[Brickie]

Are the neighbours houses pretty much the same as yours? 

By that I mean,do they seem like they were built as part of the same development?

[Mr Punter]

Unless the existing structure is showing signs such as cracking, doors and windows not fitting etc. the existing footings are probably OK for what you propose.  A trial hole later will confirm.

[Tyke2]

8 minutes ago, Mr Punter said:

Unless the existing structure is showing signs such as cracking, doors and windows not fitting etc. the existing footings are probably OK for what you propose.  A trial hole later will confirm.

This is true.

[Leelou]

2 hours ago, Brickie said:

Are the neighbours houses pretty much the same as yours? 

By that I mean,do they seem like they were built as part of the same development?

Yes they are. 

 

In regards to footings, we plan to lift the concrete slabs in the garden which are directly at the back of the house. Could we begin to dig to expose the existing footings to get an idea of what they're like, presuming this will help any survey as well as save on having to get a mini digger in? 

 

[Russell griffiths]

I would think you could do the trial holes yourself by hand, contact a local structural engineer and tell him you want a brief site meeting to discuss the likelihood of having acceptable foundations, 

i would think you could get a good feel for the project without spending more than £500. 

 

 

[oldkettle]

I dug the hole to expose the foundation then called the local building control officer. He was very nice, arranged a site meeting and confirmed he had no issues with our plans. 

[Leelou]

Thanks for the replies everyone, its been a great help to get us started. 

[Leelou]

Evening all, 

 

I've been talking to a friend this evening who is a retired developer. He was of the opinion that it didn't matter if the existing footings were suitable or not as concrete pillars could be built within the existing structure to support a second storey, including the potential use of RSJ's. 

 

Whilst taking his opinion with a pinch of salt, what is the benefit of digging a pit to inspect the footings given the above?

 

Thanks

[Tyke2]

1 minute ago, Leelou said:

Evening all, 

 

I've been talking to a friend this evening who is a retired developer. He was of the opinion that it didn't matter if the existing footings were suitable or not as concrete pillars could be built within the existing structure to support a second storey, including the potential use of RSJ's. 

 

Whilst taking his opinion with a pinch of salt, what is the benefit of digging a pit to inspect the footings given the above?

 

Thanks

Any column would need to be supported, either from the existing footing or a new specialist pad to support the new column. Or if adding extra load to the existing structure a structural survey would need doing.

But unless its on filled ground or piled, I would think that the foundation used for a bungalow would support a second storey.

In any case you really need to know what's down there.

[newhome]

9 minutes ago, Tyke2 said:

But unless its on filled ground or piled, I would think that the foundation used for a bungalow would support a second storey.

In any case you really need to know what's down there.

 

Wouldn't the SE / building inspector need to see what's down there too? I had to dig down to expose the foundations for the extension and where they joined the main house as they had been filled in before anyone looked at them. It was a pain as it meant digging down about 2 metres. 

[Ferdinand]

On 18/09/2018 at 12:39, Leelou said:

The reason for asking my initial question is that if we find it's not cost effective to improve the footings, we'll just make do with the bungalow and expand on the single floor.

 

That your neighbours have done it suggests that it is likely to be cost effective.

 

Quote

Whilst taking his opinion with a pinch of salt, what is the benefit of digging a pit to inspect the footings given the above?

 

It's not him that suffers the consequences if he is wrong. Do ya feel lucky ? ?

 

To me it is a bit like not getting laser surgery until spectacles vanish from conferences frequented by opticians and doctors.

 

Welcome to the Pleasure Dome.

 

F

Edited September 23, 2018 by Ferdinand

[Ferdinand]

On 18/09/2018 at 10:21, Leelou said:

Hi all,

 

We are just starting out with the goal of adding a second storey to our newly purchased bungalow. Both neighbours have already gone up a floor and our bungalow has stairs with a dormer in the roof already. We want to take the roof off and build an additional floor but before doing so, need to find out what the existing structure and footings can take. Do we engage a structural engineer, dig some holes and find out before engaging an architect?

 

Thanks

 

Depending on when it was built, it may be worth having a word with Building control as owner, and seeing if you can have a view of any records they hold.

F

[Leelou]

Thanks all, it makes sense now. Regardless of the build options, we need to see what's under there and that means digging a pit.

 

I've already contacted the local building control officer and am waiting a reply.

 

 

[Onoff]

I think @Construction Channel ended up underpinning as his footings were shallow. Probably a video.

[Leelou]

A productive few days at the bungalow with two visits from a very friendly building control officer. After digging four trial pits and having them inspected we now have a much better idea of where we stand and what extra is going to be needed. We've now engaged an architect, have relayed the feedback from the officer and are waiting for a quote. Thanks for your advice!

[Tyke2]

Hi. Just keep in mind that the BC officer is not a structural/geotechnical engineer. Personally I would have used an engineer who is going to have his PI insurance in place to advise you on the foundations.

[the_r_sole]

.

Edited September 26, 2019 by the_r_sole

[Tyke2]

18 minutes ago, the_r_sole said:

yeah, I agree - specialist foundations and work on existing buildings really want to be done by a structural engineer, you'll find they can design the most cost effective and practical solution to a problem, building control might tell you something that will work but it's not going to be the best solution

BC might say what might/should be Ok. But if something went wrong , they would have not take any responsibility.

On some big housing estates we would have full geotechnical soil reports produced, full engineer designed foundations approved etc. The BC would always turn up and say "Id like them 6 inch deeper and 6 inch wider", as a standard comment. We would refuse and get the engineer to confirm the design to them.

 

Edited September 27, 2018 by Tyke2