New Workshop Build Advice

[placks]

Hi All.

I now have a space where I can fit a 4.2 x 3.6m workshop shed. I'm a pretty good DIYer but have not tackled a self build like this before. There is so much information, opinions and threads about other builds that it does get quite overwhelming.

So I thought id start my own thread to plan and record progress.

Base:
It will be located were an old (level) patio is so id rather use what's already there instead of replace it with a new sub base (concrete etc). The patio is raised above soil and will be surrounded with gravel.

Been reading a lot about lifting the wooden floor off the ground as much as possible to preserve the life of the building which I get but I don't want to eat into too much of 2.5 mtr height limit.

So wondering what the options are or what other people have done?
Any experience or thoughts on eco bearers?

As the sub base is raised and there wont be much paving sitting past the edges of the floor or roof overhang, I am pretty confident that will be able to avoid too much water ingress on the sub base etc.

A previous small shop bought storage shed was sat directly on a concrete base in another part of the garden for 6+ years and was recently taken down and rebuilt somewhere else and the floor and structure were both fine.

Insulation:
insulation / sound proofing are a requirement as id like all year use but also want to maintain neighbourly relations.
any insulation not to be used if having electrics?

Floor:
I've seen people do PIR board between floor joists then boarded over with OSB or PLY. I'm thinking about using 2x4 for the floor joists. if I used 50mm PIR board for insulation would the 50mm gap that's left be sufficient for air flow?

Walls:
2x4s for sufficient for Stud work?

Roof:
I know someone that fits EPDM roofs so would be able to get this done relatively cheap (use offcuts and fitted as favour) is that a good option?

Siding:
T&G v shiplap?
Do different sidings requiring different insulation?
What about vapour / moisture barriers?

I think that's pretty much all I can think of to get me off the ground

Thanks for any advice input people are able to give, its really useful.

 

[Glitch]

With my very limited recent experience I'd say check out Mike G's shed build advice. It sets the standard.
I discovered it too late so I've made it harder for myself.

What I can say is 4x2, 24" on centre is fine for the walls. It gives you space for a decent thickness of insulation, as well as a sturdy frame. I did 16" on centre but I overengineered it.
Floor and ceiling joists you'll need to think about the spans involved. I did my floor and ceiling with 5 x 2 - my build is a shed with attached BBQ shack - both 2.7m x 2.7m. My structure is just under 15 square meters and 2.5m high so avoided need PP and building regs, more by luck than judgment.

I've built on an existing shed base and patio slabs. I've used heavy duty adjustable supports.
On reflection and given how much I've splashed out I'd have done it differently. Also make sure the walls are over the edge of the base to avoid splashback.
Also consider what you are going to do with rainwater off the roof.

I used 100mm Kingspan to insulate under the floor - covered with 18mm OSB.

For the wall and ceiling insulation I went a bit off piste and used eco friendly sheep's wool. Very easy to handle but shed smells like a stable

I use EPDM on 18mm OSB for the roof. Really pleased with the result and did it all single handed. Easy to fit, looks good and lasts a long time.

From inside to outside the layers are OSB, studwork with insulation, breathable building wrap, battens, decorative boards.

I caused a stir by using OSB, moisture barrier (plastic sheet), stud with insulation, OSB, building wrap, battens, boards. A risk of interstitial condensation, but only if you believe OSB is a moisture barrier. It's not, but if I did it again I'd drop the outer layer of OSB.
I followed a couple of shed builds on YouTube that did it that way.

There's far more experience on here to provide further advice but that's my two penneth.

 

[placks]

With my very limited recent experience I'd say check out Mike G's shed build advice. It sets the standard.
I discovered it too late so I've made it harder for myself.

What I can say is 4x2, 24" on centre is fine for the walls. It gives you space for a decent thickness of insulation, as well as a sturdy frame. I did 16" on centre but I overengineered it.
Floor and ceiling joists you'll need to think about the spans involved. I did my floor and ceiling with 5 x 2 - my build is a shed with attached BBQ shack - both 2.7m x 2.7m. My structure is just under 15 square meters and 2.5m high so avoided need PP and building regs, more by luck than judgment.

I've built on an existing shed base and patio slabs. I've used heavy duty adjustable supports.
On reflection and given how much I've splashed out I'd have done it differently. Also make sure the walls are over the edge of the base to avoid splashback.
Also consider what you are going to do with rainwater off the roof.

I used 100mm Kingspan to insulate under the floor - covered with 18mm OSB.

For the wall and ceiling insulation I went a bit off piste and used eco friendly sheep's wool. Very easy to handle but shed smells like a stable

I use EPDM on 18mm OSB for the roof. Really pleased with the result and did it all single handed. Easy to fit, looks good and lasts a long time.

From inside to outside the layers are OSB, studwork with insulation, breathable building wrap, battens, decorative boards.

I caused a stir by using OSB, moisture barrier (plastic sheet), stud with insulation, OSB, building wrap, battens, boards. A risk of interstitial condensation, but only if you believe OSB is a moisture barrier. It's not, but if I did it again I'd drop the outer layer of OSB.
I followed a couple of shed builds on YouTube that did it that way.

There's far more experience on here to provide further advice but that's my two penneth.

Hi Glitch - Thanks for the input, sounds like a good build and some useful information, especially about what you would do differently etc. Hopefully the stable smell fades over time . How do you find the sheep's wool is performing for insulation and sound?

RE the rainwater, I am probably gonna put guttering to a water butt....

 

[Glitch]

Can’t comment on the insulation yet because I don’t have a door!
Neighbour runs a joinery business. He’s making me a ledge and brace frame.

I’ve got guttering and bought a couple of cheap water butt kits from Wickes. They are small and quickly filled up so you end up with the problem of getting rid of the water.
I was thinking hoses to be able to let it run off into flower beds. Currently I let it run out into a narrow border between the shed and the fence. It drains reasonably well without eroding the soil. The plan is to fill that with gravel. I could maybe put in French drain arrangement if it becomes a problem or use the hose idea.

 

[placks]

Can’t comment on the insulation yet because I don’t have a door!
Neighbour runs a joinery business. He’s making me a ledge and brace frame.

I’ve got guttering and bought a couple of cheap water butt kits from Wickes. They are small and quickly filled up so you end up with the problem of getting rid of the water.
I was thinking hoses to be able to let it run off into flower beds. Currently I let it run out into a narrow border between the shed and the fence. It drains reasonably well without eroding the soil. The plan is to fill that with gravel. I could maybe put in French drain arrangement if it becomes a problem or use the hose idea.

Yeah good point on the butt filling up. I do have two raised beds that are near the shed so could drain straight into them or I have 2ft gravelled area around 3 sides of the shed area so could drain to that

 

[placks]

I've built on an existing shed base and patio slabs. I've used heavy duty adjustable supports.

/QUOTE]

Hi Glitch

Which adjustable supports did you go for?

Thanks

 

[Glitch]

I used QuickJacks HS

I also added some Jouplast decking risers that I had spare too.

The QuickJacks are well made and can take a lot of weight.
Took a while to get everything as level as it could be. They compensate for the fall on the patio.

A compromise compared to a proper brick base.

I live in a terraced house so couldn’t face digging up the old shed base and patio and having it all carted through the house.

 

[Pedropete]

I used QuickJacks HS
I also added some Jouplast decking risers that I had spare too.
The QuickJacks are well made and can take a lot of weight. Took a while to get everything as level as it could be. They compensate for the fall on the patio.

Apologies for dredging up an old thread but I'm faced with a similar situation in needing to relocate a smallish (3x2m) but quite heavy storage shed and place it on an asphalt driveway that falls in two directions by about 50-60mm.

Asphalt surface and sub-base are both of poor quality and prone to pressure-marking. Trying to avoid putting pads down first as that'd raise peak height >2.5m but unsure if the QuickJacks will cope with gradient without digging in on the uphill side of the foot-plate. Also looked at Haven Timber's 'BaseFeat' as the foot-plates are a ball & socket design and self-levelling.

Did you have to shim the QuickJack foot-plates to have them sit flat on the paving or do they flex enough to cope?

 

[Glitch]

The fall on mine is very slight.

I didn't, but probably should have spent more time and effort getting them sitting perfectly flat and shimmed any gaps. There are no signs of worrying gaps or instability.
They do have a little play in the top plates but not much.

My old shed base and the patio slabs are a solid base. The QuickJacks are very unlikely to sink.

I wouldn't use them on soft or unstable ground.

 

[Pedropete]

The fall on mine is very slight.

I didn't, but probably should have spent more time and effort getting them sitting perfectly flat and shimmed any gaps. There are no signs of worrying gaps or instability.
They do have a little play in the top plates but not much.

My old shed base and the patio slabs are a solid base. The QuickJacks are very unlikely to sink.

I wouldn't use them on soft or unstable ground.

Good to know, thanks. Was considering using some 100mm recycled composite post left from last workshop build but would still need pads and doesn't offer any adjustment after the fact. Will likely go with the QuickJacks and paver-pads and see if I can drop the roof pitch to allow for extra height. Thanks again.

 

[thetyreman]

insulation won't be enough to soundproof it, you'll need something like mass layer vinyl for that and use multi layers of MDF on the inside, ideally with MLV sandwitched between the layers, it can get expensive fast.

 

[sawdustandwax]

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