Converting a Shed into a Workshop

[Sneezle]

Hi all,

First time posting here but I have been following this forum for tips for a while.
I could really do with your advice on how to properly insulate a pre-built shed. I can see there are a lot of posts already about this and I have read a lot of them but because I am quite new to being handy and I couldn't see anything directly comparable to lift ideas from, I thought I would be best asking directly.

Scenario

In short, until very recently, we were due to move to a larger house, but due to a chain collapse, that plan has now fallen through. Due to an imminent new arrival (!) we aren’t likely to be moving again for a few years.
I have been using the loft as a mini workshop for a while but this will need to be repurposed as an office space.

I have a nice 12x8 pre-fab shed that I purchased in 2020 which is currently sitting largely unused. I want to find a way to turn this shed into a small workshop to practice some small woodwork and keep my homebrew kit in.

I know this is a small space for a workshop but it’ll be a substantial upgrade from the space I currently have (which is basically a very small table in the loft). I have watched a whole bunch of youtube videos and read a lot of DIY books about converting a shed into a workshop and basically just find myself a bit overloaded by all the conflicting information and basically paralysed by indecision and the fear of getting it wrong and having to either redo it all, or having a rotting mess within 2 years!

Shed

The Shed is 12x8 and is tongue and groove. Timber is treated and is rated for 10 years +. The roof is metal and the building seems watertight. The shed sits on timber bearers on an uneven concrete floor.

The wall batons are 45mm and the ceiling batons are 70mm – which is frustrating as they don’t seem to be conventional sizes for the majority of insulation that I can find in the post 2020 world without making a large bulk order.

I have already had a crack at doing something to the floor (as I needed to start moving some things in from the loft asap!) which I go into below.



Planned use of space

As above, I would like to use this space as a small workshop. I will be running electrics from the house to the shed for lighting and plan on putting in a few plug sockets for power tools.

I would like it to be warm enough to work in over winter or at least so it doesn't freeze or get damp, so homebrew and tools are safe in there. There is enough scope to run a little oil radiator as well.

I don’t have many power tools as I am just starting to learn and I expect if there ever comes a time where I want something bigger, I think we’ll either be getting ready to move house, or I will have gained more knowledge and experience and will have the confidence and ability to build my own to spec.

I would love to take the shed with me but it was difficult enough just getting it in place so it will probably stay where it is when (if) we go so realistically I am looking for a permanent insulation installation.

Current Insulation Plan

Floor



I am a comparative DIY novice but I have lined the floor with a Wickes standard vapour barrier, some water resistant soft foam flooring on top of that and then covered it with a 5mm rubber floor. It seems to have taken some of the edge off the cold and is robust enough for me to do work on it without breakages or damage to the floor.

Unfortunately, the shed was installed and fitted before I knew I would want to use it for a workshop and the floor is fitted with countersunk nails throughout, so I won’t be able to get under it and fit insulation to the floor framework without the risk of damage to the shed.

I did think of a floating floor but as the shed is a pent roof with 203 at it’s highest and 190 at it’s lowest (I am just over 6’2!), so I don’t have space left to fit a floating floor.

Unless you all think there is a good reason, I don’t plan on touching the floor again.

Walls


Ideally, I see that I would have lined the outside of the shed with a barrier. However, the cladding is in situ and nailed in place with countersunk nails, so lining the entire thing isn’t really an option for me (I will be doing this work mostly alone). I was hoping I could use an air gap between cladding and the working space inside to mitigate the fact there was no barrier.

I was originally thinking of insulating the walls using the internal batons as a framework, using nails driven into these to provide a friction fit for 40mm polystyrene leaving a small 5mm air gap between the internal cladding and the inside of the wall. After this was fitted, I was planning on covering any joins in aluminium tape, stapling a vapour barrier on the batons over this (with an overlap) and then finishing by covering with hardboard, OSB or thin plywood (to give enough strength for a french cleat system in due course) before sealing and painting.

Having read into it, I see that the strong recommendation is that polystyrene and electricity don’t mix at all, so I am planning on replacing the polystyrene with PIR (Kingspan or whatever I can find at the moment) but this requires a bit of a rethink. PIR seems really expensive at the moment compared to poly but I want it to be safe to use.

For PIR, the only sizes that seem commonly available without an expensive bulk buy are 25mm or 50mm.

With the batons in the wall being 45mm, I think it will have to be 25mm PIR throughout with a 11mm air gap between internal cladding and wall and then place cut 9mm thick OSB panels to cover the PIR and then seal round the gaps between OSB panels with caulk. Will that actually provide any benefit?

Roof

For the roof, the batons are 75mm, so I was thinking of using 50mm PIR with a 25mm air gap from the top of the roof (again, friction fit the insulation with nails), cover with vapour barrier and then hardboard over it.

Should note, the roof does not sit cleanly on the walls – there is a bit of overlap all around with spaces set out that are wide enough for me to fit my hand down. I assume this is to allow for airflow, so I will try not to block these gaps with insulation and will try to find some mesh to fit over the gaps to prevent insects from coming in.



Windows

For the windows – which are single panel glass, I was thinking of just sealing any gaps in the frames with expanding foam and sticking on a cheap plastic liner on the inside of the glass.

Power

Finally I have been thinking about how to route the power, so what I am planning on doing is drilling a hole in the floor for the power cable to go through alongside the inside of one wall (with a channel cut in the PIR to facilitate this), sealing the hole the cable comes through in the floor with expanding foam and then pulling the cable through the OSB and having everything run from a central point there with the cables on the outside of the OSB. Does that sound sensible? An electrician will fit this for me, but I think I need to have a rough idea for the design and the walls insulated and sorted before I get him over.

As you can see, I have thought about this but I don’t know anyone who is DIY orientated and so don’t have anyone to bounce this idea off of!

Could you let me know what you think about the plan so far? Does this sound like it will work or is this complete overkill for the intended use?

Thanks so much for any advice you can offer! Everything gratefully received!

 

[Cabinetman]

Mike G did some wonderful drawings and instructions on everything you need to know, as far as I know it was done as a sticky but it couldn’t have been very sticky as it’s dropped off and I can’t find it easily. Ian

 

[Jameshow]

I think your over thinking it.

I'd just get 25mm pir and put it push fit between the studs. Perhaps carefully remove the bottom cladding beam and run a length of alu tape over the bottom timber so that any water that gets past the cladding runs down the foil faced insulation and out the bottom of the shed. Perhaps leave a 3mm gap at bottom of first plank of cladding.

9mm OSB to inside.

Power run in trunking. Or just extension cables clipped to the walls.

Cheers James

 

[Fitzroy]

Do as James said.

You can’t do the job properly due to your start point so just do the best you can for the minimal outlay.

If you were thinking of living in it then you’d be stuffed as the amount of moisture would likely cause a problem with condensation. But you are not, your using it for occasional use. Any moisture will dry out between uses.

 

[Jones]

If you staple a multifoil insulation to the studs and joists, tape the joints and line with OSB that will give better insulation than thin foil board or polystyrene, don't pull it tight so it can expand into the void. I don't know what the price comparison would be at the moment.
Regarding the home brew my brother uses an old fridge as an insulated box to put the brew bin and a fish tank heater in. The results are good.

 

[niall Y]

Hi there,
I have just completed work on a very similar project myself - not as a workshop, but as a usable outside room. The shed I have insulated and lined, was first tackled 11 years ago, but owing to rot. has been rebuilt in the last few months. I started from a slightly better position - in that the shed when purchased . had already been lined wit roofing felt. I'm sure you could line the inside across the T&G and up and over the battens with a breathable felt.
The insulation is 25mm Celotex panels, and the lining is 6mm ply. This has been painted and any gaps filled with an acrylic caulk. It is surprisingly cosy and wind proof.
One thing that I did do at the outset was to install a double glazed PVC window - which has made all the difference. The window design for sheds is very poor, and is usually the first part to rot. You can often find used D/G units cheaply or for free, and it might be well worth adapting the existing opening to fit what ever suitable window you can find
My floor is fairly thick rebated boards which stops any drafts coming, and I find that the lack of insulation isn't a problem. I'm sure your floor will be far superior
Most of the problem I've had with rot was caused by a leaking roof- though many of the outside boards had also rotted through. On the plus side it had lasted 11 years in a very wet part of Wales. Wishing you luck Niall

 

[MARK.B.]

Keep it simple and as cheap as you can,save the cash for your new home workshop when you move, it is unlikely that even a nice insulated shed will add any real value when you come to sell. Besides you will need all your cash for the new arrival (congrats on that) I found out two days ago that a new grandchild is on the way and it has already cost a fortune,.

 

[Sneezle]

Thanks all, I really appreciate it.

I think as some of you have said, I have been overthinking it. Sometimes you just need a straight answer!

Based off what you have all suggested I am thinking of using the multifoil (thanks Jones for the tip - I didn't even know that existed!) as that works out cheaper for the space, will fit neatly in the gaps and claims to provide the equivalent to 50mm PIR.

Plan then is staple foil to inside of joists and walls, and then cover walls in 9mm OSB and seal gaps. Electrics I'll run as James suggested, via trunking.

 

[Jmontc]

A 50 x 50 batten fixed to the existing wall studs and ceiling rafters should give enough room to use 100mm rockwool insulation- I built a timber framed workshop and that is what I did
i think you will need to close off the gap between walls and roof otherwise you will just lose all your heat and waste all your work on the insulation - that’s how I did it 8 years ago and no issues with rot (yet?)
lining the walls with osb is a great move - easy to place tool storage hangers etc and also take surface electrics. I have no issues at all with condensation on saw tabes or tools (and heat only used infequently)
my issue is that it takes a long time for my oil filled electric radiator to bring my workshop (14 ft x 14ft) to a comfortable temperature
good luck

 

[sawtooth-9]

Do all the insulation you like / can. That's good.

But the BEST insulation is to "dress for the occasion" !

The best way to keep warm, is to wear "layers" best if natural fibres.
One of the "secrets" is to keep warm feet- and the best way to do this is with a couple of layers of sox inside shoes with a thick sole. But, the blood supply to the feet comes through the legs, so some "long johns" or similar as an under garment works wonders.
It is easier to keep a "small human " warm, than to warm a large room ! It's also much cheaper !
Even in Bellingen ( mid north coast of NSW ), we get "freezing" in winter !

 

[Gordon Tarling]

All well and good, but that won't keep his homebrew warm during the winter! Also, it won't help glue or paint to dry.

G.

 

[sawtooth-9]

All well and good, but that won't keep his homebrew warm during the winter! Also, it won't help glue or paint to dry.

G.

The homebrew solution is simple - drink it before it's got the chance to get too cold !
If you have enough homebrew, you won't worry if the paint or glue dries or not.

 

[caitrionahoran]

I

Hi all,

First time posting here but I have been following this forum for tips for a while.
I could really do with your advice on how to properly insulate a pre-built shed. I can see there are a lot of posts already about this and I have read a lot of them but because I am quite new to being handy and I couldn't see anything directly comparable to lift ideas from, I thought I would be best asking directly.

Scenario

In short, until very recently, we were due to move to a larger house, but due to a chain collapse, that plan has now fallen through. Due to an imminent new arrival (!) we aren’t likely to be moving again for a few years.
I have been using the loft as a mini workshop for a while but this will need to be repurposed as an office space.

I have a nice 12x8 pre-fab shed that I purchased in 2020 which is currently sitting largely unused. I want to find a way to turn this shed into a small workshop to practice some small woodwork and keep my homebrew kit in.

I know this is a small space for a workshop but it’ll be a substantial upgrade from the space I currently have (which is basically a very small table in the loft). I have watched a whole bunch of youtube videos and read a lot of DIY books about converting a shed into a workshop and basically just find myself a bit overloaded by all the conflicting information and basically paralysed by indecision and the fear of getting it wrong and having to either redo it all, or having a rotting mess within 2 years!

Shed

The Shed is 12x8 and is tongue and groove. Timber is treated and is rated for 10 years +. The roof is metal and the building seems watertight. The shed sits on timber bearers on an uneven concrete floor.

The wall batons are 45mm and the ceiling batons are 70mm – which is frustrating as they don’t seem to be conventional sizes for the majority of insulation that I can find in the post 2020 world without making a large bulk order.

I have already had a crack at doing something to the floor (as I needed to start moving some things in from the loft asap!) which I go into below.

View attachment 122057

Planned use of space

As above, I would like to use this space as a small workshop. I will be running electrics from the house to the shed for lighting and plan on putting in a few plug sockets for power tools.

I would like it to be warm enough to work in over winter or at least so it doesn't freeze or get damp, so homebrew and tools are safe in there. There is enough scope to run a little oil radiator as well.

I don’t have many power tools as I am just starting to learn and I expect if there ever comes a time where I want something bigger, I think we’ll either be getting ready to move house, or I will have gained more knowledge and experience and will have the confidence and ability to build my own to spec.

I would love to take the shed with me but it was difficult enough just getting it in place so it will probably stay where it is when (if) we go so realistically I am looking for a permanent insulation installation.

Current Insulation Plan

Floor

View attachment 122059

I am a comparative DIY novice but I have lined the floor with a Wickes standard vapour barrier, some water resistant soft foam flooring on top of that and then covered it with a 5mm rubber floor. It seems to have taken some of the edge off the cold and is robust enough for me to do work on it without breakages or damage to the floor.

Unfortunately, the shed was installed and fitted before I knew I would want to use it for a workshop and the floor is fitted with countersunk nails throughout, so I won’t be able to get under it and fit insulation to the floor framework without the risk of damage to the shed.

I did think of a floating floor but as the shed is a pent roof with 203 at it’s highest and 190 at it’s lowest (I am just over 6’2!), so I don’t have space left to fit a floating floor.

Unless you all think there is a good reason, I don’t plan on touching the floor again.

Walls

View attachment 122058
Ideally, I see that I would have lined the outside of the shed with a barrier. However, the cladding is in situ and nailed in place with countersunk nails, so lining the entire thing isn’t really an option for me (I will be doing this work mostly alone). I was hoping I could use an air gap between cladding and the working space inside to mitigate the fact there was no barrier.

I was originally thinking of insulating the walls using the internal batons as a framework, using nails driven into these to provide a friction fit for 40mm polystyrene leaving a small 5mm air gap between the internal cladding and the inside of the wall. After this was fitted, I was planning on covering any joins in aluminium tape, stapling a vapour barrier on the batons over this (with an overlap) and then finishing by covering with hardboard, OSB or thin plywood (to give enough strength for a french cleat system in due course) before sealing and painting.

Having read into it, I see that the strong recommendation is that polystyrene and electricity don’t mix at all, so I am planning on replacing the polystyrene with PIR (Kingspan or whatever I can find at the moment) but this requires a bit of a rethink. PIR seems really expensive at the moment compared to poly but I want it to be safe to use.

For PIR, the only sizes that seem commonly available without an expensive bulk buy are 25mm or 50mm.

With the batons in the wall being 45mm, I think it will have to be 25mm PIR throughout with a 11mm air gap between internal cladding and wall and then place cut 9mm thick OSB panels to cover the PIR and then seal round the gaps between OSB panels with caulk. Will that actually provide any benefit?

Roof

For the roof, the batons are 75mm, so I was thinking of using 50mm PIR with a 25mm air gap from the top of the roof (again, friction fit the insulation with nails), cover with vapour barrier and then hardboard over it.

Should note, the roof does not sit cleanly on the walls – there is a bit of overlap all around with spaces set out that are wide enough for me to fit my hand down. I assume this is to allow for airflow, so I will try not to block these gaps with insulation and will try to find some mesh to fit over the gaps to prevent insects from coming in.

View attachment 122055

Windows

For the windows – which are single panel glass, I was thinking of just sealing any gaps in the frames with expanding foam and sticking on a cheap plastic liner on the inside of the glass.

Power

Finally I have been thinking about how to route the power, so what I am planning on doing is drilling a hole in the floor for the power cable to go through alongside the inside of one wall (with a channel cut in the PIR to facilitate this), sealing the hole the cable comes through in the floor with expanding foam and then pulling the cable through the OSB and having everything run from a central point there with the cables on the outside of the OSB. Does that sound sensible? An electrician will fit this for me, but I think I need to have a rough idea for the design and the walls insulated and sorted before I get him over.

As you can see, I have thought about this but I don’t know anyone who is DIY orientated and so don’t have anyone to bounce this idea off of!

Could you let me know what you think about the plan so far? Does this sound like it will work or is this complete overkill for the intended use?

Thanks so much for any advice you can offer! Everything gratefully received!

have used PIR on a timber framed holiday chalet and it can be bought in different thicknesses. I put it between the main gram and created an air gap on the outside by battening before fixing new cladding. Also used roofing membrane under the cladding. I realise this may be difficult from the inside. Look on eBay for single sheets of PIR. People also sometimes sell sheets or off cuts from bigger projects or even pre-used pieces. I would avoid polystyrene- if burnt it gives off cyanide gas. Hope this helps in some way.

 

[caitrionahoran]

‘Gram’ should read ‘studs’apologies.

 

[ShedJohn]

Looking to piggyback on the Op's thread.

Have tried to go through previous threads as much as possible but seems to be conflicting advice being give. My shed, which was already built when we moved in, is similar in some ways to the one in the OP as 8x12 except it has an apex roof. Internal frame is 45mm on Walls and Roof. Electrics and lights have already been installed too. There is no external air gap/membrane in between the cladding and the interior. 2 Single pane windows. Have provided some photos to give some more context.

I'm looking to insulate the shed as it gets pretty cold in winter (and hot in summer) when working on small items like busy boards for the kids but also would like to use it as a home office a couple of days a week as I'm currently doing that from the bedroom and having my laptop and a temporary desk sat there all week there is doing my wife's head in (!). Would also likely be keeping a small fridge in there too.

Other threads have said that for a shed conversion you must absolutely have membrane/air gap/insulation/vapour proofing/OSB but some of the replies on this thread seems to suggest not bothering with that given starting point of the shed and just use insulation/OSB instead.

I'm open to the idea of fitting additional battens to the existing studs to allow for more room to fit insulation but conscious that the existing electrics would then be in a recess? From an effort/cost vs effectiveness/ease tradeoff am I better off just going down the multifoil and OSB only route (and is multifoil safe to sue with electrics?)? Also not sure how the wall panels in between the frame should be ventilated (regardless of which option is chosen) - would I need to install a vent into every panel?

Many, many thanks in advance for anyone's thoughts and recommendations on this.