workshop insulation help

[cornucopia]

hello folks there seems to be a lot of knowledge on these boards about workshop heating and insulation etc so here my problem

my workshop is a concrete section garage with an asbestos lux corrugated roof- this was built about 9 years ago by the previous owners of the house.
the internal dimensions are 9' by 8' by 6'6" at the sides and 7'6" at the centre of the ceiling. I put 2" vertical battens on the walls and ceiling filled the area between these with normal roof insulation then put a 1/2" fibre board over the top.
the problem is it gets very hot in the summer compared to a friends brick built garage/workshop. the walls and ceiling seem to heat up in the morning and stay hot all day- if you put your hand about 12" away from either the walls or ceiling the heat is incredible.
i'm wondering wether to strip it out this summer and place this stuff behind the battens then re-apply the roof insulation then use 1/2" plaster board over the top.
my long winded question is ........
do you think this will help or are there any other materials/things i could use which would be better

thanks
george

 

[Grinding One]

Paint the outside of building White to reflect the sun white shingles do the same

 

[cornucopia]

thanks but unfortunatley thats not an option

 

[crazylilting]

I haven't learned the U factors that you use here in the uk but i do know how it is measured in Canada in R factors.

You say you are using 2 inches of Bat insulation. Standard construction in Canada is 6 inch cavity wall, which when insulated gives you an R 22 rating. Which is standard and R44 in ceilings as more heat loss is lost through the roof.

In the summer temperatures are similar and insulation works the same as it does here. People only plan to keep things warm in the winter, and because BTU losses are less here then in Canada people don't put enough insulation in because they don't think they need it.

Your situation is a perfect example of this.

The other thing that is important in a ceiling is ventilation. First your roof then air space then insulation and then a vapor barrier. As you are having issues with height already in your shop I would consider looking into the highest R value you can find in the thinnest material you can find. to make sure you get ventilation between your roof and the insulation. this also means you need to have air flow in this space.

I wish i knew the U value system that the UK uses but it's to hard to wrap my head around. Everything in Canada was done in BTU's and the relative R factor or (resistance to loss).

The walls in your building are a loss cause as they are concrete. You would need more insulation then you would want to give up in space. But i'd be interested to see what others will say about this as I have a cinder block building that i'd like to insulate.

 

[MikeG.]

George,

welcome to the square side!!

I'm afraid that the plan you propose will probably make things worse, not better. It is only another form of insulation..........I think it needs an airspace either die of it to work effectively anyway...........and so will contain the heat in your shed even better.

So, lets get to the bottom of your problem............

Where is the heat coming from? They certainly are absorbant surfaces that the building is made with........so is it just when the sun shines on it that it gets too hot?

Have you a south facing window, or is it all from the 40 grit sandpaper you hold against your lumps of spinning wood? :wink: Or is it just the kilowatt of energy that the average adult male gives off?

The unfortunate thing is that your insulation should ideally be outside the masonry. If your shed was externally insulated and clad, then the problem would disappear as the shed's internal temperature tended towards the ambient average...........ie it would stay warm in the winter and cool in the summer.

When we know where the heat is coming from, we'll solve this for you George.......have a good think about when it gets hot (ie what sort of weather conditions), when it doesn't get hot, what the orientation is, overshading, internal heat sources (I think from memory your lathe is the size of Texas and therefore gives off a bit of heat just running the monster motor). Tell me also about ventilation.

Mike

 

[MikeG.]

Crazylilting,

U = 1/R

Mike

 

[wizer]

Tell me also about ventilation.

George has something akin to a port hole

 

[MikeG.]

Crazylilting,

U = 1/R

Mike

.........oh, and the vapour barrier is a bit of a red herring in a shed, where there is very little water vapour produced. The vapour barrier is simply to prevent interstitial condensation (the water vapour in the air condensing within the structure) by reducing the amount of vapour in the cold zone.

 

[crazylilting]

Thanks Mike, Still hard to wrap my head around it.

I thought about insulating the outside of the concrete but the OP said that painting the outside wasn't an option so assumed that insulating it would be less likely.

Edit:

The reason for the vapor barrier is for condensation produced by two different temperatures outside and inside. More of an issue in winter. With all these people putting more insulation in their attics now days they will find that they will end up with black mold due to this problems of no vapor barrier.

 

[MikeG.]

Well possibly, but lofts are designed to be extremely well ventilated, and that does resolve those issues.

The problem with vapour barriers for the lay person is that they typically think that the wettest air is outside.........whereas, the wettest air is almost always inside a dwelling. The vapour barrier aims to keep the damp air from getting into the structure (from the inside of the house).

As I said, completely different problems in a shed.

Mike

 

[cornucopia]

thanks for the replies- my workshop is in the back of the garage- as you stand looking at the back wall (over the top of my lathe) i'm facing south and the east is to my left side. I installed a 4" bathroom extractor fan at the highest point on the south wall which ventilates the space but doesn't help with the heat- i open my only window on the west wall which if its windy helps a little.
the lathe gets warm after a few hours of use but not fry and egg hot. the lathe is 2hp and theres two 6' strip lights no other motors or machines are in there with me other than hand tools.

heres a pic of me taken on the west side of the workshop- you can see the wall costructioin and the small 4" vent of the extractor- I cant paint the roof or walls white- due to concerns over "what will the neighbors think" and the pebble dash on the walls continuously falling off

 

[Paul.J]

George.
When you've done what you've gotta do,could you not do a stable type door on the door you have so you can leave the garage door open slightly or whatever to get some air flow through.Dependant on your neighbours,and daughter of course. :roll:
I think your garage is the same style as mine and i find that when i do this it does help.
I have replaced my roof though with ply now as i did find the cement corrugated type did seem to attract the heat,and also lined the walls with 18mm ply.

 

[cornucopia]

hello Paul it does help when I can get a through draft- but i worry about noise with my neighbors.

one of my customers is an air con installation chap- he has offered to air con it for me with a split system- but I thought that the internal part of the air con unit wouldn't last two minutes in the dusty enviroment of a wood workshop-
would you guys agree or could that be the (expensive )anwser?

 

[crazylilting]

What about putting a fan in a box and filter direction pointing out at the highest point in the shop and a fan pointing in on the north side floor level pointing in? Nothing to fancy just functional and secure enough for mice not to get in.

I know what you mean about making to much noise. Some of the shops i've seen on here blow my mind as to how the neighbors put up with them. I'd not even be able to go into a shop like many of them. It would feel like i'm in a fish bowl.

 

[wizer]

I was thinking the same thing. An extractor fan the other way around blowing air in from low down. It should create a through flow of air through the workshop. You could put the fan in the side door.

Tho it would probably make a dust storm in the workshop.

 

[duncanh]

I cant paint the roof or walls white- due to concerns over "what will the neighbors think" and the pebble dash on the walls continuously falling off

Have you tried approaching the neighbours to see if they'd mind a white building?

One thing I considered for my shed was to install a sheet of material or even wooden boards over the top of the existing roof leaving an air gap between (20cm or so). The theory being that the air gap will heat up and the air can escape at the sides or even through a gap in the ridge, rather than the heat landing on the shed roof. This is based on a survival technique I saw on some tv programme which used 2 layers of parachute material with an air gap between.

At the moment in summer I open the window (which is actually no longer a window, but a couple of hinged plywood portholes) and suspend a large fan in front of it to blow cold air in. Whilst turning I don't have the extractor on so there's not much noise escaping.
When it comes to sanding I close the plywood so the extractors can be started up.

I installed a small fan lowdown in one wall and another high up in the angle of the roof. The theory was that the top fan would expel hot air and the low one would bring in cool air from the shaded side of the shed. It may work with larger fans but I used what I had in and they were too small.

 

[wizer]

One thought George, Do you really think the neighbours will be offended by a white garage? I don't think I'd be offended by it. In fact I think I'd prefer it to ordinary pebble dash. I think you'd have to spray it but you're the expert in that dept.

 

[cornucopia]

One thought George, Do you really think the neighbours will be offended by a white garage? I don't think I'd be offended by it. In fact I think I'd prefer it to ordinary pebble dash. I think you'd have to spray it but you're the expert in that dept.

I'm not sure- but if you do ask then the can of worms will be open and unable to be shut again :? also a pure brillant white garage would stand out like a sore thumb in the middle of suburbia- maybe a flashing light on th eroof would be less conspicous?!!?!?

I have a 10" input fan which i have to use when i am working in cellars etc I think i will rig that up today and what diffrence it can make.

thanks for all the replies

 

[wizer]

my whole house is white. But I see what you mean, if everything else is pebble dashed then it will stand out. Personally I don't care about the neighbours. In fact I don't actually have any at the moment

 

[John. B]

Just a theory :roll: but if you put a false ceiling ie an air gap with an extractor fan at each end, one drawing air in the other expelling into the open air, would that not work.

John. B