Thread: Simon's New Shed

Originally Posted by lyricnz

I think my gap would be at least that much, see photo below, but I take your point. Since this is retrofit, it's going to be a bit of a challenge to get the Insulshed there without cutting it to pieces. The blue things are screwed to the corro, and the purlins are screwed to them. Ideas? Besides lots of cutting slits in the insulation...

IMO if you cut the Insulshed, I don't think it'll be effective - it needs to be a continuous moisture barrier. Ours was installed by removing the external cladding, installing the Insulshed, and then re-applying the external cladding.

> Ours was installed by removing the external cladding, installing the Insulshed, and then re-applying the external cladding.

Ooooh, I can't see myself doing that, solo and with a brand-new shed. Maybe I can approach the problem in the other direction? Elevate the ply a little on blocks to allow relatively free airflow behind the sheets? Then they would be open and the top and bottom, and even at the sides on the vertical beams.

Hi L. The moisture problem is usually because the warmer air inside the shed meets the colder outside air (particularily at night) at the tin. Just like bathroom windows, moisture forms and if it can't evaporate (or migrate through the material) you have a problem. What you are trying to do is insulate the underside (or inside) of the metal, providing a thermal break between the two areas of differing temperature. Air flow is secondary. All this assumes you have no actual leaks but it is a new shed so safe to assume this will be the case. I apologize if this is something you already know, lots of people don't.

The biggest problems with steel sheds is the air stops flowing at night and if it continued the humidity issue would largely go away.

Hi Chris. I few years ago now I had clients with a back verandah, open on 2 sides. Roof was exposed corrugated iron on top of battens on top of rafters. Because of the condesation that collected on the underside of the roof and then dripped onto the deck, the deck was unusable until around lunchtime. My advice was to insulate with foil blanket before lining with cement sheet. This was done and they have enjoyed their back deck ever since. I believe that air movement is not enough.

Any thoughts on the second-best (vs removing the external cladding) solution to retrofit a moisture barrier (Insulshed? foilboard?) given the construction below? I can't separate the purlins from the blue vertical things, as the screws don't go through the corro, just through the flanges of the blue things. Maybe horizontal insulation with slits to go around the junctions, and some goop/tape to make it as sealed as possible? I really should have ordered wall insulation with the shed

Or I could just sandwich the insulation between the purlins and the plywood (air gap between tin and insulation)


IMG_3056.jpgIMG_3057.jpg

Do you gents spray closed cell foam in buildings? A couple three inches will stop all condensation, keep you warm/cool and deadens the metallic sound. Hang the plywood and Bob's your uncle. You just have to find a local company with the equipment to do the work.

Pete

Originally Posted by QC Inspector

Do you gents spray closed cell foam in buildings? A couple three inches will stop all condensation, keep you warm/cool and deadens the metallic sound. Hang the plywood and Bob's your uncle. You just have to find a local company with the equipment to do the work.

Pete

Unfortunately Spray foam, in Australia is really expensive,well was when i looked into it about five/six years ago.
If it wasn’t so expensive I would definitely go the spray foam option.

Cheers Matt.

Hi Lyricnz. I would use foil blanket, tucked in against the corry, cut to fit between the blue battens, run vertically and with fibreglass against the corry and slver paper facing the inside. Then I would fix the plywood to the horizontal purlins, between posts. This air gap will separate the extrenal wall assembly from the internal one and stop the condesation building up on the metal. The foil blankets sole responsibilty is to insulate the inside of the corry. If you want to insulate the shed for temperature, you could install a layer of batts between the foil blanket and the plywood.

I've decided to do what I did on my last shed - use Foilboard 20 (sealed with the special tape).

Foil Insulation - Rigid Foil Insulation Panel - Foilboard

A bit of a spacer to keep it off the corro, and seal any gaps. Probably won't put bats between the ply and the foilboard, since I'm only going to clad 1/2 the shed anyway.

Today's status: walls are all up, garage doors are mounted, today they are putting the Insulshed on the roof, and the roof corro on.

Next: flashing on the corners, around the person-door, etc. Add the bearers for the mezzanine, and the mezzanine surface itself.

Yes I am wondering if I could afford to use Foilboard for the ceiling and the top part of the walls. It is not just the cost of the Foilboard but also access to the ceiling. My shed should come with the foil blanket but there are no trees or anything to stop the sun beating down on the roof. The roof is going to house solar panels so there never will be any shade on it. Hence I thought a gap and then foilboard might really increase the insulation and perhaps even reduce some sound emissions. I doubt I'll have budget but we'll see how we go.

If I won lotto I would build a tropical roof over the whole shed. Which is unlikely since I buy a ticket about once a year at most.

Originally Posted by lyricnz

Today's status: walls are all up, garage doors are mounted, today they are putting the Insulshed on the roof, and the roof corro on.

Without photos, it never happened.

Tip on foilboard - bunnings are more expensive than (for example) these guys.
Foilboard(R) Green Rigid Insulation Panels - Pricewise Insulation
Hit bunnings up for a price-match (+10%)

if you have solar mounted on the roof, won't that act as a bit of an extra insulation layer (to the tin, and the foil blanket, beneath it)?

The yellowtongue for the mezzanine arrived today, and is being mounted right now. Epoxy flooring can't do it for a couple of weeks, so I probably won't do the ply until after the epoxy floor is down. Photos later today!