Garage foundations

[Sambob15]

Hello there,

Our 1960s prefab garage is getting a bit knackered so we're looking to replace it, either with another prefab or a proper brick one if it's not stupidly expensive. About 10ft wide x 20ft long.

Had a few quotes in so far.

Had a very nice chap round today to quote for a brick garage and he's got a gap next month which this job would fit nicely into, so I am expecting him to price keenly.

He's quoting for a single-skin brick garage on a concrete pad/slab/raft, with similar dimensions to what we have now. Which seems fine.

Some questions though, as we need to make a decision pretty swiftly...

- we are on clay soil. Is a concrete pad sufficient? He seems to think so, and only one of the builders has quoted us for strip foundations while the rest are in the concrete camp
- for a relatively simple structure like this (the garage is not attached to anything) is it ok not to bother with drawings? Or am I just leaving myself open to problems by not having them?
- is any planning permission/other permission needed, or does anyone need to be informed, or are we ok because there's already a garage there and it'd be replaced with a very similar structure?

Thanks a million for any replies.

 

[noseall]

I really can't see the point in opting a raft foundation over a strip.

However, if these people are promising a designed proper raft (where the external brickwork is set below ground level and a thickened edge beam) but it is their intention to stick a poxy slab at ground level, then be prepared for a lot of damp inside along with all the problems with crappy slabs and the issue of the 'toe' gathering water etc.

 

[^woody^]

A proper slab/raft will be fine on clay, and even preferred as it will bob up and down nicely on clay.

If this is a "design and build" you can just specify exactly what want and let them get on with it.

 

[Sambob15]

I really can't see the point in opting a raft foundation over a strip.

However, if these people are promising a designed proper raft (where the external brickwork is set below ground level and a thickened edge beam) but it is their intention to stick a poxy slab at ground level, then be prepared for a lot of damp inside along with all the problems with crappy slabs and the issue of the 'toe' gathering water etc.

So far I've been told it'd be a hardcore layer, concrete and DPM...

 

[Sambob15]

A proper slab/raft will be fine on clay, and even preferred as it will bob up and down nicely on clay.

If this is a "design and build" you can just specify exactly what want and let them get on with it.

This is interesting, I'd never thought a slab might be desirable. If we proceed with the builder we've had the most interaction with so far it sounds like everything would be written up properly.

Thanks for your replies

 

[Leofric]

I would say it is always best to have a drawing of what you propose to build then you and the builder both know what is going to be built ,but no doubt some 'bugger it just do it merchants' will say otherwise.

 

[Sambob15]

Well having done some more reading it's now looking like a brick-built garage might not be possible without going down the planning permission route. This document suggests a brick-built garage would only be classed as permitted development if it was less than 2.5 metres tall, as it would be situated close to the boundary. If anyone could have a glance and confirm that I've understood it correctly it would be much appreciated:

(e) the height of the building, enclosure or container would exceed -
(i) 4 metres in the case of a building with a dual-pitched roof,
(ii) 2.5 metres in the case of a building, enclosure or container within 2
metres of the boundary of the curtilage of the dwellinghouse, or
(iii) 3 metres in any other case
The height of the building, enclosure or container should be measured from the highest
ground level immediately adjacent to the building, enclosure, or container to its highest
point.
The height limit on a ‘dual-pitched roof’ of four metres should also be applied to buildings
that have ‘hipped’ roofs (slopes on all four sides).
If any part of the building, container or enclosure is within two metres of the boundary of
the curtilage of the house, then the height limit for the total development is restricted to 2.5
metres if it is to be permitted development.

 

[John D v2.0]

Yes keep it below 2.5 from the original ground level if it's near the boundary.

 

[^woody^]

This document suggests a brick-built garage would only be classed as permitted development if it was less than 2.5 metres tall, as it would be situated close to the boundary

It wont matter if it's from brick or gingerbread for permitted development.

"Height" in this context is eaves height and ridge height, in both cases from ground to the tile at those points. Not ceiling or roof height or suchlike.

 

[Ian H]

It wont matter if it's from brick or gingerbread for permitted development.

"Height" in this context is eaves height and ridge height, in both cases from ground to the tile at those points. Not ceiling or roof height or suchlike.

So on the same building could you have a 2.3mtr high eaves upto the boundary then a 4.0mtr high ridge 2.0mtrs in from the boundary?

Edit,

Probably not because of this:

If any part of the building, container or enclosure is within two metres of the boundary of
the curtilage of the house, then the height limit for the total development is restricted to 2.5
metres if it is to be permitted development.

 

[nickjb]

As you have now read, its 2.5m max if any part of the building is within 2m of a boundary. And as mentioned brick or wood makes no difference.

Planning permission may be granted, especially if you only want to go a little higher. A few hundred quid on the cost of the project for a bit more headroom may be worthwhile.

 

[^woody^]

As you have now read, its 2.5m max if any part of the building is within 2m of a boundary. And as mentioned brick or wood makes no difference.

Planning permission may be granted, especially if you only want to go a little higher. A few hundred quid on the cost of the project for a bit more headroom may be worthwhile.

That's right. People seem to fear the planning process, will compromise and live with an inferior design just to get it PD compliant, when they could potentially get a much better building for relatively little more time and expense.

 

[Leofric]

That's right. People seem to fear the planning process, will compromise and live with an inferior design just to get it PD compliant, when they could potentially get a much better building for relatively little more time and expense.

Quite right , there seem to be a lot of people on here limiting themselves by what is permitted development. Planning applications for relatively small domestic works aren't usually that complicated for people like building designers such as architects and architectural technicians . They need to be given due consideration obviously .

 

[Sambob15]

Sorry I didn't really explain properly - the reason I specified that brick would need planning permission is that a concrete garage would fall below the 2.5m limit, so wouldn't be affected by the rules. Whereas a brick garage would likely be above that limit.

Given that funds and time are tight, we'll probably go down the concrete garage route in light of this discovery. Which isn't a problem - it was just nice to think we could have a brick garage where I could actually attach things to the walls!

Glad we discovered this now anyway, before getting the ball rolling.

 

[^woody^]

Typical garages, extensions, in fact any single storey building at ground level will have eaves no higher than 2.5m, so I can't see how that is a problem.