Large Garage/Workshop plans

[WestcountryWonderer]

Here is what I'm hope to achieve, any comments or suggestions will be most welcome. I have an architecht coming out next week to have look at feasibility for planning etc. but I want to do as much of this myself (i.e. all of it) so trying to get advice and ideas from as many sources as possible!

 

There is curretnly a single garage around 6m x 3m, 3.5m high to the ridge (2.5 to the eves), single skin block.

I  want to knock it down and replace with a much larger version, 7m x 10m, keeping to around 3.5m to the ridge but I'd like to achieve around 3m ceiling height inside to allow for a car lift in the future.

For that area I know it will need to comply with building regs and I'm planning either stick built timber frame or SIPS to maximise internal floor space for overall footprint and for speed/ease of doing it all myself.

 

The biggest constraint I currently have is that it will have to be around 300mm from the boudary which is where I think SIPS might be a better choice as they'll meet the fireproof requirement without much of a fight?

The second biggest constraint I think is the spans as I'd like to keep it totally open inside to no pillars in the middle of the place to support roofs. Not sure if this is being a bit too optomistic though.

 

Foundations: Would I likely need trench fill foundations for something of this size with timber frame or SIPS? Or would I likely get away with raft foundations? What's the score for aproval of this, is it purely a structural engineer job?

Floor slab will need to be around 200mm deep reinforced concrete to allow a lift to be fitted later. This is where I'm thinking that trench foundations might be simpler. Pour the foundations, a course or two of blocks then infill the perimeter for the floor?

I am thinking about GEOCELL floam glass for under the slab, it is spec'd for the extension we have planning for and should kill two birds with one stone. Has anyone used it before? Or am I better going for a more traditional MOT then celotex then slab?

 

Walls: I have looked at Eco SIPS, can anyone recomend any others? I was thnking their 119mm panel build up from the ouside as follows:

UPVc wood effect cladding (fibre cement on the boundary wall if required for BR)>38mm vertical battons>breather membrane>SIPS panel>vapour control layer>25mm batton>plasterboard & skim.

Do I have the membrane & VCL the right side of the battons?

Being a garage I'd like something more substancial than plasterboard to fix 'stuff' to, would OSB or ply meet building regs or would it have to be plasterboard?

 

If I went for stick build timber it would be:

UPVc wood effect cladding (fibre cement on the boundary wall if required for BR)>38mm vertical battons>breather membrane>25mm horizontal battons with 25mm celotex between>100x50 studs at 400mm centres with 100mm cellotex fill>11mm OSB>vapour control layer>25mm batton>plasterboard & skim.

Same questions for this option and do I need a sheet of OSB on the outside as well?

 

Roof: I'm thinking either EPDM or square box sheeting?

either 144mm SIPS or stick built again. Pretty much the same build up as the walls for both options.

 

Aside from that I'm thinking of a couple windows in one wall, a pedestrian door and a roller door.

I like the idea of a couple of clear panels in the roof to let a little light in but not sure if this will over complicate it for not much benefit.

The only other thing that I am not sure either way on at the minute is air circulation. would it be worth fitting a cheap single room MVHR unit to keep some air flow and stop any damp stagnent air sticking in there? Something like this:

https://www.extractorfanworld.co.uk/vent-axia-435004-hr100rs-single-room-heat-recovery-unit---suspended-ceilings-2726-p.asp

Or is that a bit over kill?

 

I'm hoping to get some more detail and skitches together next week, but as an outline, what do people think?

SIPS might just be winning in my mind as although they'll be a little more expensive, it will be quicker and more straight forward...

[joe90]

Well that sounds similar to the one I built, the only difference is I used roof trusses so no car lift ?. If you used a ridge beam you would have room for it. Trench founds, block with pillar construction, within PD rules, with the overhang of the roof I was able to keep it to 2.5m but the door clears 2.5m. I was worried about condensation from the metal roof and asked about fleece lined panels but they only really work in barn type construction (lots of air flow. Instead I simply used roofing felt under the metal roof and no condensation issues. It’s draughty enough to stop any mould, but cold in the winter (thermal longjohns ?).
 

 

Edited July 23, 2021 by joe90

[WestcountryWonderer]

Thanks.

That looks very nice!

I'm aiming for 2.5m clearance through the door (my Land rover is just over 2.3 high so need that and little spare for comfort!).

Trusses are possibly an option for mine, but not sure if I'd spend more money getting them calculated and made than I would just stick building or going for SIPS which would be easier to keep the clearance.

The insulation for me is partly having to comply with BR but also partly trying to keep a fairly stable temp summer and winter while also keeping the dampnesss out to stop things rusting!

 

aread wise I could get in under PD as the garden would be big enough. But the height would prevent that I think and the proximity to the boundary definately prevents it. I cant afford to move it further off the bournary as that will be too restrictive so planning permission is the only option. Hence having an architecht take a look

[Russell griffiths]

Have you looked at tool insurance, I know that many insurers will not insure tools over £2000 value unless in a brick built building. 

[Russell griffiths]

I would build it on an insulated raft and use icf blocks for the walls. 

I wouldn’t entertain a wooden structure if your thinking of welding and grinding. 

Sips panels will also be very poor at keeping any noise you make inside. 

[joe90]

29 minutes ago, WestcountryWonderer said:

not sure if I'd spend more money getting them calculated and made than I would just stick building

Trusses worked out cheaper for me ?.

[Johnnyt]

I've just built a 7m X 8m garage to accomodate our motorhome.

Trusses used on top of traditional 2 skin walling.

The openning is 3150 high as is the wall plate but centally the roof is higher.

See link

 

https://sketchfab.com/3d-models/26599a-d7f8d1d343ce4a569ef90ef284ce2bb5

[WestcountryWonderer]

1 hour ago, Russell griffiths said:

Have you looked at tool insurance, I know that many insurers will not insure tools over £2000 value unless in a brick built building. 

 

I hadn't thought about that if I'm honest, but part of the reason for thinking about SIPS is that I seem to remember a national homebuilding webinar wherre the SIPS manufacturer went to great lengths to ephesise that they are classified as 'traditional building method' for insurance etc. i.e. they have certificates etc etc and not just someone has got a pile of timber and nailed it together.

 

1 hour ago, Russell griffiths said:

I would build it on an insulated raft and use icf blocks for the walls. 

I wouldn’t entertain a wooden structure if your thinking of welding and grinding. 

Sips panels will also be very poor at keeping any noise you make inside. 

 

I hadn't considered ICF but I will look into it. Especially as I've just seen a social media post from the architecht who's coming to look next week that she has just done a training day with an ICF supplier...

This is also where I'm thnking that plasterboard and skimed walls and ceiling are the only option internally. With any joints sealed with firee proof silicone.

 

1 hour ago, Johnnyt said:

I've just built a 7m X 8m garage to accomodate our motorhome.

Trusses used on top of traditional 2 skin walling.

The openning is 3150 high as is the wall plate but centally the roof is higher.

See link

 

https://sketchfab.com/3d-models/26599a-d7f8d1d343ce4a569ef90ef284ce2bb5

 

Thanks for that, what size timbers did you use there? and were the trusses manufacturerd or did you make them on site?

I want to keep the roof as low as possible to help with not upsetting neighbours and not blocking out too much sun from my garden. But it's good to hear that someone has done a 7m span as that was one area I wondered if I'd come unstuck in.

 

The main reasons for avoiding block and brick is the time it will take for me to build it.

 

Lots of food for though from here though so thank you, exactly what I was after with this post!

[Russell griffiths]

Insurance wise you are talking about two different things. 

Standard construction satisfies the property insurance, for example the built structure and how it stands up. 

Contents insurance is totally different, try to get insurance on an outbuilding not connected to your house, I have found previously it very hard to get cover over £2000, and almost impossible to get cover for a non brick construction. 

[WestcountryWonderer]

That is interesting about insurance and not something I had really thought that much about.

Although it might be me being a little neigheve but my house insurance doesn't cover any item over 2k unless it's been listed anyway. so I'm not sure what the difference would be.

the house insurance is due soon so I'll give them a call to see what they have to say