Garden building.

[Jsmith7]

Going to be building a garden building next year. 
roughly 7m x 3m which will leave 1m gap to each neighbours fence and the back fence.

 

I’m wanting a concrete base just not decided on the best or cost affective ie. Insulated concrete base and a course of two bricks or concrete base 2 courses of bricks and insulated on top of concrete. 
I need 2m height at the back lowest part of flat roof. 
also I’m thinking 3x2 timber frame work, a membrane then 2x1 battens and Shiplap cladding on top. 
Ply lined on the inside and maybe plaster board on top of that. Half the building is going to be a cage and avairy breeding room. The other half a garden room. 
insulated metal roof panels for the roof. 
double glazed windows and doors. 
 

any think I’ve missed or could be done better or cost effective?

 

many thanks 

[saveasteading]

A shed could simply go on a 100mm slab, on dpm on hardcore. With or without reinforcement,  which is to limit cracking.

For an occasionally inhabited building I would be adding a downturn (footing) to the perimeter. Definitely mesh in it, maybe insulation, but there isn't much point in insulating the slab without the walls and roof too.

[Jsmith7]

The roof is 80mm insulated panels. 
and I’ve got 50mm in the walls. 

[Bozza]

There are so many options for something like this.  There’s that garden rooms bloke on YouTube that advocates cementing threaded rods into the ground and building off that.  Also your skill level - what you can do yourself - costs of materials etc etc.

 

I’d never built anything before so my small barn was DIY constructed as follows ( apologies if using wrong terminology).

 

for founds I did a strip foundation with deeper dig at 6 points  - four corners plus mid way (8x4 building).  Couple of courses of brickwork around.  Foundations.  In filled with hardcore, sand, dpc, solid insulation then did a concrete hand pour over top to create concrete floor.   Treated timber bottom plate 4x2 fixed to perimeter brickwork. 

 

I built a series of modular 2.4 x 1.2 wall panels out of 4x2 with 9mm osb on face.  These were bolted to the bottom plate.  Built the gables same way, then the roof timber, beams etc for a 45 deg roof.  Clad structure  in breathable membrane.  Insulated the framework and put airtight polythene stapled inside.

 

Whole thing clad in combo of steel sheeting and leftover Siberian  larch from house.  Interior not yet finished but thing has not moved even in storms.  Inside it’s not cold in winter and not hot in summer.  
 

saved a fortune building it myself and really enjoyed doing it learning many skills I hadn’t done before other than usual diy around home.

 

 

 

 

[oliwoodings]

I wouldn't bother doing an insulated slab for a garden building or even doing brick courses. For mine I just did 100mm MOT, dpm, 100mm reinforced slab. Then bolted sole plates down with oversized dpc underneath, which I later lapped up underneath the breather membrane of the walls. For the floor buildup, I put more dpm down over the concrete, taped to the inside of the dpc. Then put 100mm PIR on top, taped with foil tape. Then floating 18mm t&g osb subfloor on top of that (glued).

 

Really simple to DIY, really effective.

[Jsmith7]

I might go with the insulation on top of concrete. 
ideally want the bricks for vermin control and rain splash. 

[saveasteading]

5 hours ago, Jsmith7 said:

ideally want the bricks for vermin control and rain splash. 

I agree that this would be excessive for a garden tool shed, but its a good idea for something more substantial.

On a big timber frame once, the supplier wanted a concrete upstand to the perimeter. quite a fiddly and costly thing to do. 

I proposed precast concrete lintels , bolted down, which also allowed us to pack them to dead level and to adjust the line if necessary.

The supplier was really happy with it, as of course it fitted perfectly.

So was I as it was very much cheaper than in-situ and a bit cheaper, but a lot stronger, than brickwork.

 

about £10/m

 

[Bozza]

On 24/12/2023 at 21:18, saveasteading said:

proposed precast concrete lintels , bolted down, which also allowed us to pack them to dead level and to adjust the line if necessary.

That’s a really smart idea particularity fur those who haven’t laid bricks or blocks before.

[saveasteading]

55 minutes ago, Bozza said:

a really smart idea

Thanks. One of those things when you are the designer and the contractor. 

Also the fun of it, as well as saving money.  But there's a risk with anything new and untested.

I'm sure plenty of people would have declined to approve it, but it was all my risk.  I'm sure I'd have heard if there was a problem.

 

I seem to recall that the price was great too, once the merchant recovered from being asked for a price for 100+ m of these.

 

I think hitfix nails is all we used, just to pin them in place, because uplift wasn't an issue.

[oliwoodings]

On 27/12/2023 at 18:31, saveasteading said:

Thanks. One of those things when you are the designer and the contractor. 

Also the fun of it, as well as saving money.  But there's a risk with anything new and untested.

I'm sure plenty of people would have declined to approve it, but it was all my risk.  I'm sure I'd have heard if there was a problem.

 

I seem to recall that the price was great too, once the merchant recovered from being asked for a price for 100+ m of these.

 

I think hitfix nails is all we used, just to pin them in place, because uplift wasn't an issue.

I wish I had discovered this approach before I did my garden building, so smart!! Would have saved me the headache I now have of water running back under the sole plates (I changed the shape of the building slightly after the slab had been done, meaning the slab is larger than the footprint).