Green Building Forum - garage foundations Mon, 25 May 2026 22:11:31 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176811#Comment_176811 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176811#Comment_176811 Sat, 25 May 2013 18:39:47 +0100 djh
So we're looking at 2.5 m deep strip or trench foundations with a suspended concrete slab, or a raft with 1.25 m hardcore underneath it, or piles or .... Now that's an awful lot of concrete, muck away and money.

I'm sure that will give me a garage that doesn't move, but why should I care? Even more, since the drive outside it *will* move, why would I want a garage that doesn't? Can anybody point me to somewhere that explains the rationale for what appears to be idiocy? Or better yet, tell me how to avoid it.]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176812#Comment_176812 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176812#Comment_176812 Sat, 25 May 2013 19:00:52 +0100 tony garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176813#Comment_176813 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176813#Comment_176813 Sat, 25 May 2013 19:01:58 +0100 Ed Davies Posted By: djhand is over the size for permitted development, so we are subject to building regs.What's PD got to do with building regs? Genuine question - building regulations apply to some things which are permitted development and some things which require planning permission aren't covered by building regs so what linkage do you have in mind?]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176814#Comment_176814 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176814#Comment_176814 Sat, 25 May 2013 19:17:13 +0100 tony garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176817#Comment_176817 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176817#Comment_176817 Sat, 25 May 2013 19:47:49 +0100 djh Posted By: Ed Davies
Posted By: djhand is over the size for permitted development, so we are subject to building regs.
What's PD got to do with building regs? Genuine question - building regulations apply to some things which are permitted development and some things which require planning permission aren't covered by building regs so what linkage do you have in mind?
Sorry, you're quite right. I got sloppy, there's no connection. There are two facts: we are subject to building regs, because the floor area is too big. We are subject to planning, because of the position, but we have that permission. Sorry for the confusion.]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176818#Comment_176818 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176818#Comment_176818 Sat, 25 May 2013 19:58:46 +0100 djh Posted By: tonyhow about building it on a raft?
That's the current theory. The 1.25 m hole to be dug and filled with hardcore is my problem, and because of NHBC rules, the hole has to be over twice the size of the garage.
Posted By: tonyHow near to the boundary are you with it?

Pretty close. About 0.5 m. That's another problem.]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176819#Comment_176819 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176819#Comment_176819 Sat, 25 May 2013 20:00:50 +0100 Jonti
if it is a timber garage then a Tony asks, what about a raft? I would not think building regs will demand a certain type of build but rather that it is proven that the foundations meet the stipulated standards.

Jonti]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176822#Comment_176822 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176822#Comment_176822 Sat, 25 May 2013 21:40:19 +0100 djh Posted By: Jontiif it is a timber garage then a Tony asks, what about a raft?
I thought I already answered that?]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176823#Comment_176823 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176823#Comment_176823 Sat, 25 May 2013 21:45:38 +0100 tony garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176825#Comment_176825 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176825#Comment_176825 Sat, 25 May 2013 21:52:48 +0100 djh Posted By: tonyI see no difference between timber or masonry on a raft may be different design of raft, some houses are built on rafts
Right, neither does NHBC. The difference to my mind is that if you tilt a timber frame building, it should still be standing if it's been properly braced, but masonry will topple. There's no question a raft is adequate; it's the volume of the hole that's required underneath it that is the problem.

Does anybody have any other suggestions, or a link to the rationale for these standards?]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176840#Comment_176840 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176840#Comment_176840 Sun, 26 May 2013 08:03:17 +0100 Jonti Posted By: djh
Posted By: Jontiif it is a timber garage then a Tony asks, what about a raft?

I thought I already answered that?

Started my reply before you posted yours to Tony so did not see yours. BRs are based on calculations of required standards as far as I am aware. If you can prove how you wish to build meets this then it has to be accepted.

Jonti]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176860#Comment_176860 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176860#Comment_176860 Sun, 26 May 2013 16:14:50 +0100 djh
Loading

A1. (1) The building shall be constructed so that the combined dead,
imposed and wind loads are sustained and transmitted by it to the
ground:
(a) safely; and
(b) without causing such deflection or deformation of any
part of the building, or such movement of the ground, as will impair
the stability of any part of another building.
(2) In assessing whether a building complies with sub paragraph
(1) regard shall be had to the imposed and wind loads to which it is
likely to be subjected in the ordinary course of its use for the purpose
for which it is intended.

Ground movement

A2. The building shall be constructed so that ground movement
caused by:
(a) swelling, shrinkage or freezing of the subsoil; or
(b) land-slip or subsidence (other than subsidence arising
from shrinkage, in so far as the risk can be reasonably foreseen), will
not impair the stability of any part of the building.

As far as I can see there is no requirement there that the building shall not move. I can't see anything in the guidance either. I can see that it makes some sense for a house, but where does the idea that this is a reasonable goal for a detached garage come from?]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176865#Comment_176865 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176865#Comment_176865 Sun, 26 May 2013 20:08:29 +0100 Peter_in_Hungary garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176866#Comment_176866 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176866#Comment_176866 Sun, 26 May 2013 21:14:11 +0100 PaulJ
It may be that NHBC are doing warranty and regs. Request to them that the garage is excluded from warranty cover, which they will agree to. It won't hurt resale and may reduce premium.

WRT b regs, they have a square area beneath which the building is excluded. Nothing to stop you building another building of the same max size next to it, with a 50mm gap. Knock through at your leisure. Really, b regs are not that interested in outbuildings. Don't waste concrete. Do a slab with mesh or beam and block on a 1m deep strip footing.]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176870#Comment_176870 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176870#Comment_176870 Mon, 27 May 2013 09:07:18 +0100 Gotanewlife
Obviously fully Italian wouldn't bother with the strip footing at all and I would have to stand over them to ensure sufficient metal went in....except that I would do it myself.]]> garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176881#Comment_176881 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176881#Comment_176881 Mon, 27 May 2013 14:19:19 +0100 SteveZ garage foundations https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176889#Comment_176889 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10711&Focus=176889#Comment_176889 Mon, 27 May 2013 16:13:55 +0100 djh
NHBC are not providing a warranty, but their standard gets thrown around by people when discussing foundations. Regs are interested in outbuildings, except when they are excluded, usually by reasons of the small size exceptions. e.g. garages under 30 m² internal floor area are excluded. Mine is larger because it's a double and Lifetime Homes specifies minimum size over that. It isn't next to the house, so there are no considerations about knocking through.

SteveZ's experience sounds all too familiar. I'm planning a timber garage with a metal roof, so it should be fairly light and strong in the sense of coping with movement.

It sounds like I need to have a chat the the BCO and see what he will accept. I was just hoping to find some additional background first.]]>