Buying New Workshop - Advice on Damp Proofing / Insulation?

[rjb]

Hi,

I'm planning to buy a new shed / workshop and I would appreciate some advice.

I'm currently working in a brick built single garage, but I have very little working space as the garage also is used for storage (and a little hoarding). Apart from the lack of space, the main problem with the garage is that it gets very cold and damp in the winter months. The damp has affected some of my materials (mainly MDF) and it's not a particularly nice working environment.

I'd like to buy a ready made shed / workshop about 14' x 10', but the more I look into it the less certain I am about what I should go for as I've received lots of contradictory advice. I've found prices for standard sheds in the region of £600 - £1000, but the specifications vary and for a building with a damp proof membrane and insulation I've been quoted anything from £3000 to £6000+. This seems like a lot of extra money for damp proofing and insulation and I was wondering if I will really need this. I don't know if a wooden shed would be more or less damp than a brick garage. Also I was wondering how practical and how costly it would be for me add the damp proofing and insulation myself ...and If I did this what would be the best materials to use?

I'd be really grateful for any advice on this subject.

Thanks,
Richard

 

[mailee]

Hi Richard, I built my own wooden workshop and insulated it and fitted double glazing. I find that it is very comfortable to work in and not damp at all. It is warm in the winter and cool in the summer I am glad to say. By the way it is 24' X 13' and cost me around £1800 to build and that included everything right down to the electrics. Hope this helps. :wink:

 

[woodbloke]

Me also, same as Mailee, mine is 20x12' - Rob

 

[rjb]

Thanks for your replies. In an ideal world I'd like to build a workshop myself from scratch, but I just don't have the time at the moment (work plus two young children), that's why I was planning to buy a ready made building. Apart from possibly being more expensive I was wondering what the disadvantages were and how practical it would be to improve the building by adding damp proofing and insulation to a ready built shed.

Thanks, Richard.

 

[kafkaian]

Thanks for your replies. In an ideal world I'd like to build a workshop myself from scratch, but I just don't have the time at the moment (work plus two young children), that's why I was planning to buy a ready made building. Apart from possibly being more expensive I was wondering what the disadvantages were and how practical it would be to improve the building by adding damp proofing and insulation to a ready built shed.

Thanks, Richard.

While you're busy, would it not be better to clear out your garage of excess storage and get a couple of radiators installed? You could also make good any gaps in the doors and draught/damp proof as necessary. Where you are lacking in space, is there an option to pull tables out into the open whilst utilising temporary work covers?

Personally, I'd love the option of your single garage - as long as it wasn't too small. What sort of size is it?

 

[Shultzy]

Richard, its not a problem to insulate a bought shed. Find out the floor joist depth and wall stud thickness. Buy the appropriate thickness of insulation, rockwool or polystyrene. Turn base upside down, fill base with insulation, cover with polythene and hardboard. Lay base on engineering bricks with a layer of DPC in-between. Erect shed and fill walls and roof with insulation, cover with a vapour barrier and 12mm MDF or ply, job done.

 

[CWatters]

Reference the Building Regulations - Is a workshop classed as a habitable room?

 

[kafkaian]

Reference the Building Regulations - Is a workshop classed as a habitable room?

Or are you referring to Planning? I don't think there are issues here as long as the workshop is not 50% bigger than the available land, and less than 5 m from the house and smaller than 3m high (flat roof) or 4m (pitched roof). There is a "from road" stipulation, but other than that, workshops seems to be fairly easy to accommodate.

 

[Con Owen]

Hi Richard
If you have the shed made to your size and specification it need not be any more expensive than an off the shelf one. I purchased my shed from a local supplier. He was very helpful and made it to the size I requested, 14 x 11 with double doors overall width of 5', tar paper between the framework and cladding, 50mm polystyrene insulation between the plywood floor and the bearers. The extra cost for supply and incorporating it was £50 for the polystyrene floor insulation and £40 for the tarpaper (it appears to be good quality too). The total cost of the shed was £900 and included delivery and installation, I did the base myself using four rows of concrete blocks 18x9x4 on their side with dpm between the slabs and shed bearers. If doing again I would have tar paper incorporated between the roof cladding and bearers.
With regard to insulation I used seconds (edges might be damaged slightly) 50mm 8x4 sheets of Kingspan, foil one side and tissue the other for the walls and 25mm 8x4 foil both sides for the roof. The cost was £12 for the 50mm and £7 for the 25mm plus £25 delivery IIRC. A forum member recommended a supplier. Their name is Seconds and Company. I covered with 9mm plasterboard.
Cheers Con

 

[rjb]

While you're busy, would it not be better to clear out your garage of excess storage and get a couple of radiators installed? You could also make good any gaps in the doors and draught/damp proof as necessary. Where you are lacking in space, is there an option to pull tables out into the open whilst utilising temporary work covers?

...If only it was that simple.. Thanks for the advice, but I probably should have explained that my garage is mainly used to store stock for my growing mail order business, as well as some domestic stuff. There is no insulation at all so any heat is lost almost straight away. I've been making the best of the limited space for a long while, but I feel that the time has come to expand. Also It's not ideal storing my stock in the workshop environment due to the dust etc..

Thanks also for all the other replies, in particular Con as it sounds like you've done exactly what I want to do by damp proofing and insulating a standard shed. The Seconds & Co link is spot on! The only thing I was wondering is whether it is important to use the tar paper as this would need to be fitted when the shed is manufactured and I'm not sure if this will be possible. Do you think this is important or will the insulation board and plasterboard or ply lining be sufficient to keep the damp out?

Thanks again,

Richard.

 

[Con Owen]

Hi Richard
The shed manufacturer I used placed the tar paper between the cladding and framework and also the polystyrene between the floor and bearers as he made the shed, as I said he is very helpful. I did not do anything.
What was originally recommended to me was to incorporate a plastic damp proof membrane, but the shed supplier suggested the tar paper, it was probably easier for him to incorporate between the cladding and framework than plastic. I went along with this as my previous shed (8x8) I had for over 20 years had waterproof paper between the cladding and framework, I had no leaks and the framework and cladding was still in good condition (except where an animal had eaten a 4'' hole in one side) when I dismantled it, some of the bearers and 2 or three floorboards were rotten though. It is early days as the shed has only been up for a year, to know whether the tarpaper will be as good as the waterproof paper used on the old shed, everything appears OK at present. There are a number of useful threads on this site, a particularly comprehensive one deals with a shed made by Byron Black. Many guys were helpful to me, Mailee, Rob, Old and Woody Alan with suggestions as I was going to make a shed then changed my mind due to the fact at that time I had other priorities. Woody Alan recommended Seconds to me and showed me what he had done. The Kingspan is very easy to cut with a fine tooth saw. One other thing if you decide to use Seconds insist that they deliver using covered transport.
Cheers Con

 

[kafkaian]

...If only it was that simple.. Richard.

Fair enough, but good luck with it

 

[CWatters]

Reference the Building Regulations - Is a workshop classed as a habitable room?

Or are you referring to Planning? I don't think there are issues here as long as the workshop is not 50% bigger than the available land, and less than 5 m from the house and smaller than 3m high (flat roof) or 4m (pitched roof). There is a "from road" stipulation, but other than that, workshops seems to be fairly easy to accommodate.

No I meant the Building Regulations.

On another forum someone is trying to modify a portacabin that they use as a home office. Since offices are classed as habitable rooms they are having to get their portacabin to comply with the Building Regs standards for insulation, heating etc.

Their particular problem is with the heating. The latest regs specify a carbon emmission rating that implies a portable heater (electric or gas) isn't acceptable. For example all gas boilers in houses must now be condensing types.

My understanding is that Building Control generally look for plaster on the walls. eg if the room is plastered then they may well decide it's classed as a habitable room and subject to the full weight of the regs.

 

[rjb]

Thanks everyone for the information.

Another question I'd like to ask is what is the best type of cladding to go for? ..Shiplap or T&G? T&G appears to be more expensive than shiplap which would suggest that it is better, but I've been told that the shiplap is better as the T&G boards are prone to shrinking and coming apart. And is 12 - 14mm thickness sufficient or would it be better to go for 19mm or more?

Also, is it important to fit the vapour barrier to the outside of the frame before fixing the cladding or is it accaptable to fix this from the inside after it is built? The reason being that I'm planning to buy it ready built and some companies are unable to fit it during manufacture.

Also, I've been told that tannalised cladding is no good as it has a higher moisture content and shrinks more - is this correct?

Sorry for asking too many questions.

Thanks again..

RJB.