# Workshop - block or wood ? humidity worries..



## Bushman (30 Oct 2020)

Hello, 

I'm planning to build a small workshop at the end of my garden. I can do max 4.4 x 3.8m. I would prefer to build it in single skin block without insulation, to maximise space inside. I don't particularly care about it being warm as I won't be spending there a lot of time (hobby workshop), but I do have quite a lot of tools that would be stored there (from hand tools, electric saws etc, drills and welders). I am worried about moisture ruining my tools. Am I right to worry about it with single skin block wall and no insulation? Would insulated wooden structure be better ? Or maybe a good ventilation would do ?

Thanks


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## Argus (30 Oct 2020)

The source of passive rusting is the vapour in the air, so it doesn't really matter what type of construction you use, the temperature point at which moisture in the air condenses on ferrous metal is the point at which rust and corrosion starts.

This is a temperature known as 'Dewpoint'. (there's a lengthy explanation of the physics on Wiki). In basic terms it corresponds to the temperature point at which the air is saturated with water vapour (100% humidity) and can accept no more. When your tool's surfaces (or any other surface for that matter) reaches this temperature condensation occurs. In the presence of Oxygen in the air, oxidisation starts.

What can you do?
The most obvious answer is permanent heat. Maybe that's out of the question in a large probably uninsulated space, as is moisture removal with de-humidifiers.
Oiled tool surfaces is a good idea, but it isn't permanent and it will eventually oxidise, so you'll have to keep renewing it.

My current workshop is part of the house and I can maintain a background heat at about 15 degrees in the winter. Not warm by any stretch but enough for the tools that I have.
Previously, though, I had an unheated workshop space and I had the same problem that you have. I wasn't concerned about the working temperatures, within reason - I could wrap up - but I got fed up moving valuable tools into the house to avoid rust.

Answer?

My solution was to tackle the heat issue. I had a couple of old, tall kitchen units spare. I was able to insulate them and to install a a false perforated floor-space and small 'heater' which consisted of a couple of 15W filament Pygmy bulbs and a cheap old room thermostat set at about 18 degrees. The running cost was probably a quid or two a month if that - the contained heat from the bulbs was enough to defeat a Berkshire winter. The susceptible tools spent their time in that space. Everything else was subjected to the normal variations in temperature. That worked for me.

Good luck

P.S. Sorry, I forgot, all that was 30 odd years ago and legislation now means that you cannot get filament bulbs easily....... the modern equivalents don't emit heat......... but I guess that the idea of a small heat source remains.....


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## xy mosian (30 Oct 2020)

My first house, Saltaire, had a carpeted stone flag floor. First thing on a winters morning the dampness in the air struck through right to the bone. My solution, as above really, was a 40W light bulb left on all night. Relaced by an electric tubular 'greenhouse heater' when I found one. Did the job, just taking the chill of the air.
HTH
xy


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## Bushman (30 Oct 2020)

Thank you so much. That's really helpful and a really good advice about the use of small bulbs.
Would it change anything if I had insulated space with no heating or it wouldn't make a difference ? Do you think using aerated blocks would make a difference ? Would I be able to use , say 60w tube heater to heat (just enough) the whole space ?
Thanks


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## DBT85 (30 Oct 2020)

When the space is something that is already in existence I understand trying to make it work for you. I have to confess that I can't understand purposefully spending the time effort and money to build something from scratch that you know can give you issues from the very start.

If you want to make it single skin then fine, make it a brick plinth and timber frame above that. The frame is no thicker than the walls but at least you can put some insulation in it. 

I'm not sure a 60w heater will have nearly enough guts to heat a 16m2 uninsulated brick lined space. Argus used 30w to heat an insulated cupboard.


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## xy mosian (30 Oct 2020)

Bushman said:


> Thank you so much. That's really helpful and a really good advice about the use of small bulbs.
> Would it change anything if I had insulated space with no heating or it wouldn't make a difference ? Do you think using aerated blocks would make a difference ? Would I be able to use , say 60w tube heater to heat (just enough) the whole space ?
> Thanks



My example was to demonstrate the use of a greenhouse heater as a possible different heat source, in the event that filament bulbs are not easy to get hold of. In that they are still available and less likely to get damaged. In hind site I should have explain that.
I agree with DBT85, with nowhere near as much experience. 
xy


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## Bushman (30 Oct 2020)

I would prefer to have it in brick/block as it feels to me like more solid and longer lasting structure. Also, because the size of the shed would be over 15m2 (and within two meters of my neighbour garden) I wouldn't need to have building regs people over if I had it in noncombustible materials.

I did see the "shed Mike's way" post and it makes a lot of sense though. 
I do have an old block wall at the end of the garden (between my garden and an alleyway ). It's solid, about 2m in height. I was hoping to use it as one of the walls for my shed. If I was to build with wood, should I have it as one of the walls ? Would it not compromise the advantages of wooden insulated shed (as in cold and moisture getting through that wall)? Or should I build frame in front of it ? If so, how far (I don't want to create dead space, but also am aware if I go to close I would have problems with not enough airflow ?)?


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## Spectric (30 Oct 2020)

Hi

Have you tried an oil filled radiator with a frost setting, just enough warmth to prevent dampness.


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## Lazurus (30 Oct 2020)

Bushman said:


> I would prefer to have it in brick/block as it feels to me like more solid and longer lasting structure. Also, because the size of the shed would be over 15m2 (and within two meters of my neighbour garden) I wouldn't need to have building regs people over if I had it in noncombustible materials.
> 
> 
> I think you will need planning though?


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## Jameshow (30 Oct 2020)

Which medium are you more conversant with? 

You could build off the rear wall in either medium. Clad it with 2x2 and OSB / ply 

I'd build in timber but that's just me a carpenter 4.2m x 3.6m / 14x12ft 

Cheers James


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## DBT85 (30 Oct 2020)

Bushman said:


> I would prefer to have it in brick/block as it feels to me like more solid and longer lasting structure. Also, because the size of the shed would be over 15m2 (and within two meters of my neighbour garden) I wouldn't need to have building regs people over if I had it in noncombustible materials.
> 
> I did see the "shed Mike's way" post and it makes a lot of sense though.
> I do have an old block wall at the end of the garden (between my garden and an alleyway ). It's solid, about 2m in height. I was hoping to use it as one of the walls for my shed. If I was to build with wood, should I have it as one of the walls ? Would it not compromise the advantages of wooden insulated shed (as in cold and moisture getting through that wall)? Or should I build frame in front of it ? If so, how far (I don't want to create dead space, but also am aware if I go to close I would have problems with not enough airflow ?)?





> Building a detached garage of less than 30 square metres floor area would not normally need building regulations approval if:
> 
> the floor area of the detached garage is less than 15 square metres.
> the floor area of the garage is between 15 square metres and 30 square metres, provided the garage is at least one metre from any boundary, or it is constructed substantially of non-combustible materials.



Consider that the area restrictions on meeting building regs is related to internal area. If the max it can be outside is 4.4x3.8, with 100mm walls (of whatever construction), you're now only at 4.2x3.6 which is 15.12m2. A gnats fart over the 15m2. The 2m restriction applies to planning regs and heights, not building regs and floor area.

A more solid long lasting structure that has moisture problems, rusting tools and where you might be uncomfortable working in the deep dark winter seems daft to me. And unless you're digging half decent foundations how solid is that wall going to be over time?

Regarding non combustible materials, if its clad in fire proof stuff that goes away IIRC, it also would only need to be 1m away from the boundary to be made entirely from firelighters, though your insurance might not pay out.

If you were using that existing wall then I'd put some studs on it and put insulation in there. But I have no idea what you'd need to do with regard ventilation or damp proofing etc. 

My suggestion as someone who spent the last 5 months building a workshop is do it right and do it once. I know I'm fortunate enough to know that I'll never leave this house and can work in there for the next 50 years, but I also know that the workshop will still be there standing tall when I'm long dead, it's going to be warm, easy to keep warm and importantly dry. It's entirely different when you have to use a garage or something that's already in place, in those cases you have to make do and work around any issues. You have a largely blank slate from which to start so use it wisely. Many on here would kill burn teak to keep warm for the chance.

Sadly the person you really need to talk to is no longer on this forum. Go to woodhaven2 and ask for Mikes help there. He will largely tell you to build a plinth and frame up from there but he has a lot more knowledge of things you need answers to and is very generous with his time.


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## mikej460 (30 Oct 2020)

I have a 3.5m x 3.5 tool shed that was built with 115mm deep multicell (hollow) blocks. I renovated it, increasing the wall height by one run of blocks but otherwise untouched, there are no windows. I built a new roof of cedar shingles on t&g sarking with double battening. For the floor I laid a 120mm concrete slab over 100mm polystyrene sheets; no insulation on walls or roof and no heating - it's warm enough to work in winter and cool enough in summer; there's no rust on my tools and it never feels damp, even when it's pouring down. 

However I don't plan to use the same for my impending workshop as it would be too expensive (I'm no brickie) and I want it warmer in winter, I do plan to build a single row concrete block plinth with a timber frame structure on top and insulation in the floor, roof and walls, following MikeG 's advice. But then I'm not as restricted on size as you appear to be. 

Have you considered Superquilt insulation? If installed correctly if can replace thicker insulation and provide a vapour barrier SuperQuilt | Brands | YBS Insulation watch the videos on the website and/or Youtube
I used this as part of drylining our house during the renovation as, like you, I didn't want to lose too much internal space.


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## johnny (31 Oct 2020)

Bushman said:


> Hello,
> 
> I'm planning to build a small workshop at the end of my garden. I can do max 4.4 x 3.8m. I would prefer to build it in single skin block without insulation, to maximise space inside. I don't particularly care about it being warm as I won't be spending there a lot of time (hobby workshop), but I do have quite a lot of tools that would be stored there (from hand tools, electric saws etc, drills and welders). I am worried about moisture ruining my tools. Am I right to worry about it with single skin block wall and no insulation? Would insulated wooden structure be better ? Or maybe a good ventilation would do ?
> 
> Thanks


buy a cheap compact dehumidifier then you don't have to worry about vapour barriers and humidity. I have one of these and they collect about 0.5Lt of water every 2-3 days and keep my garden shed/workshop nice and dry AirPro Compact Air Dehumidifier 500ml (Spare parts, Power Lead Adaptor, Drawer) | eBay


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## Sheptonphil (31 Oct 2020)

Bushman said:


> I would prefer to have it in brick/block as it feels to me like more solid and longer lasting structure. Also, because the size of the shed would be over 15m2 (and within two meters of my neighbour garden) I wouldn't need to have building regs people over if I had it in noncombustible materials.



I'm agreeing with DBT85, as we live in a cold wet climate, build with a base, plinth and wood structure, and insulate it. The wall thickness will be much the same. His calculation is perfect to show you are clear of building regs as there is still the thickness of OSB to take account of. So you will legitimately be sub 15 sqm by a gnat’s fart.

I had the same dilemma, I didn’t want to loose too much space to the width, but was close to a fence. My workshop build here had to meet ‘predominantly non combustible due to its proximity or fence and as I don’t have easy access to apply preservative every few years I used Hardi Plank outside which won’t need painting for at least fifteen years.

Now it is finished (barring the final outfitting) it is a superb place to be in. Toasty warm, perfectly dry and will last longer that I have left. The cost and effort to build a flawed workspace is, to be blunt, insane. The cost and effort to do it right is the same, will give a great space to be in and will be kind to your tools.

Even if it only lasted thirty or forty years, I’d rather have that which is dry and comfortable and a great space to work in than a cold damp space that lasts forever and will be cold and damp forever without costly remedial work.


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## thetyreman (31 Oct 2020)

johnny said:


> buy a cheap compact dehumidifier then you don't have to worry about vapour barriers and humidity. I have one of these and they collect about 0.5Lt of water every 2-3 days and keep my garden shed/workshop nice and dry AirPro Compact Air Dehumidifier 500ml (Spare parts, Power Lead Adaptor, Drawer) | eBay View attachment 95471



+1 I have one of these, definitely makes a big difference


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## thetyreman (31 Oct 2020)

I would recommend insulating it, not just for your own peace of mind but it will prevent tools rusting which can be a big problem, it's not worth saving money on, you should feel comfortable in there.


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## artie (31 Oct 2020)

Lazurus said:


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> 
> 
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## artie (31 Oct 2020)

johnny said:


> buy a cheap compact dehumidifier then you don't have to worry about vapour barriers and humidity. I have one of these



Do you have any idea of the ratio of time on v time off?
Assuming it switches automatically


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## JBaz (31 Oct 2020)

If you are going to make any furniture or other items for the house in your workshop, it's important to keep the timber at or close to the temperature and humidity of your home. Otherwise the piece could shrink and warp once the central heating gets a hold of it. 
My preference would be to build a timber frame structure and insulate insulate it. At least then you can heat the building if you want to.


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## Bushman (31 Oct 2020)

Thank you for all your replies. Very informative and helpful. 
I'm edging towards the wooden shed now. I have been thinking how to play the back wall. End of my garden looks lik this:







I was wondering if I should put DPM on the back wall before I put 2x2 , fill it with insulation and then OSB? 
Would something like the drawing below work ?


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## Lockyear2810 (1 Nov 2020)

I would build the wall off the back by about 3” 75mm. 
Put some stops into your frame to put some 2” 50mm insulation in the front part of the frame, leaving an air gap to the brick wall. 
Fill around the insulation using an expanding foam gun. 
Then put a vapour barrier over the inner edge for belt and braces. 
That will stop any warm air passing through and hitting the cold brick wall. 

Also don’t sit your workshop on a large concrete plinth. 
Make the plinth a tiny bit smaller so the wooden sides can just overlap the edge of the plinth. 
That way all the water will run off the building onto the ground. 
With a large slab it will run onto the top of the slab and just sit there. 
Eventually rotting through your floor bearers.


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## johnny (2 Nov 2020)

artie said:


> Do you have any idea of the ratio of time on v time off?
> Assuming it switches automatically


I'm pretty sure its on continuously, its an uninsulated unheated diy garden shed.....but it has a tiny fan motor so a negligable current draw in mw


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## Jameshow (2 Nov 2020)

Bushman said:


> Thank you for all your replies. Very informative and helpful.
> I'm edging towards the wooden shed now. I have been thinking how to play the back wall. End of my garden looks lik this:
> View attachment 95499
> 
> ...



That looks a reasonable way to proceed. 

Why do you need s concrete floor if your a hobby woodworker? 

Unless your wanting very heavy old style machines then 18/22mm chipboard flooring over 50mm insulation will be warmer and cheaper. 

Cheers James


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## DBT85 (2 Nov 2020)

Upon what would the insulation sit? It's rigid and needs a flat surface.


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## XH558 (2 Nov 2020)

Here is some info on timber frame construction. Hope this helps but personally I would avoid block walls unless you provide a moisture barrier to prevent moisture being drawn into the the building. Tyvek is a great product. ~Then batten the walls then clad~









DIY timber frame kits


The self build helps you to reduce the costs of having a house. We offer you timber frame kits conformed to new thermal performance standards. Our timber frame fully insulated panels meet and often exceed all current building regulations.




www.space-wood.com


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