How to insulate walls for an existing steel framed shed?

[mshed65]

Hi all.

I realize this topic has been raised a number of times and i have looked at previous conversations but retrofit style projects usually have unique requirements/nuances that suggest differing approaches. I have a 9x6m steel framed shed (Stramit, portal frames at 3m crs with 64mm top hat purlins and girts at generally 1400mm crs) that was constructed on the land i purchased. I think it is circa 20 - 25yrs old. I am now looking to line some of the walls to allow building benches/shelves etc. I had built some benches against a shed wall previously by simply fixing timber plates to the shed walls - screwed from the outside through the wall sheeting - but this time would like to line the walls likely with plywood (painted) for a better look and the ability to fix anywhere to the internal walls in the future. Fixing the ply sheets to the inside will provide a 64mm air gap (top hat purlin depth) so a bit of insulation but i am looking to get a bit more insulation if possible - primarily against heat as Brisbane summer is extremely hot in there!!   

Being a standard steel framed shed construction, it does not have sisalation/wall wrap between the girts and wall sheeting so simply placing batts between the airgap (external sheet metal wall and internal ply lining) would provide insulation but also be subject to condensation from the inside skin of the wall sheeting wetting the batts so possible mould problem down the track? I have a roll of Anticon (Bradford roof blanket product, glasswool adhered to reflective foil) left over from my last reno and wonder if this could be used in any way. My current thoughts on possible solutions are as follows:

1. Cut pieces of coreflute and place between girts against wall sheeting, then install insulation batts prior to ply sheeting.

2. Fix Ametalin reflective wall insulation to inside of girts and ply sheeting directly over. Should be slightly better than air gap alone? Normally for new build, reflective side is internal and vapour barrier external beneath cladding but here which side for reflective foil given that i want to keep heat from outside coming in? Will get condensation in air gap but not really a concern. 

3. Use the Anticon i have for as far as it goes with reflective foil outside against the wall sheeting? Use 1 or 2 above for remainder?

Some may suggest using Foilboard which i will use for the ceiling if i decide to insulate it. I haven't considered it for the walls as this then does not allow fixing of future items anywhere (girt locations only) nor is it particularly great to fix ply sheets over, whether 20 or 25mm thickness foilboard. 

Would be grateful for suggestions and/or confirmation of any of my current ideas. 

[EricL]

Hi @mshed65 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about insulating your shed.

I believe the two methods you've proposed are applicable to your project. Personally, I think using corflute in combination with batts will give you superior insulation and protect the batts from moisture. I strongly recommend using the Anticon you have left so that you maximize all the resources at your disposal.

Here is a link to our best advice: How do you add insulation to a garage or shed?

Let me call on our experienced members @Dave-1 and @TedBear for their recommendation.

If you have any other questions we can help with, please let us know.

Eric

[Dave-1]

Afernoon @mshed65 

Its always nice when re-using and modding a shed/garage comes accross the feed I really like you sugestions, especially the coreflute idea to help stop condensation (I will be filing that one away for future ideas)

I like the idea of keeping the insulation off the tin, I would frame up the inside with stud walls much like I did my garage (Garage converted into library room ) With the stud walls you will be able to double some studs up fro more strength when laying out what you may want on the walls. (Always take a photof of the studwalls before the skin is put over them is def a good idea) plus sticking to standar spacing of studs.

As for the ceiling, There was a project where someone used the reflective styrofoam panels to stop condenstaion on the roof, I think it worked but will have a look later to see if I can find it and tag the member who did it.

One question I have is "How waterproof" is the floor? It looks like it is a very dry floor but something I always consider if it gets wet.

Dave

[Dave-1]

Evening @mshed65 

Found the question for condenstaion on a tin roof I was refering to. 

How to insulate a metal roof? 

Hopefully @bowmatty will be around and he can give us an update on how well the panels are holding up. It would solve your issue with the roof if it has!

Dave

[mshed65]

thanks Dave. 

You may have missed the bottom of my initial post - here again...... Some may suggest using Foilboard which i will use for the ceiling if i decide to insulate it. Known product that i've used before, and no doubt many shed builders here have. I'll do that if i get really keen. The product is fine but my roof framing layout is not conducive to the panel dimensions so would require installing an additional top hat purlin on each side of the ridge for the full 9m length plus quite a bit of sheet cutting. Possibly, but less likely than likely.

I saw your library, looks cool. One bay of my shed will be a display area but the other 2 bays (6x6m) will be workshop area. Its not living space so i will certainly not be building timber framed walls inside the shed. I've done quite a lot of building over the years having built 5 oy my own homes and 2 renos for friends. I did have some rather stiff wall installation panels a few years ago - like a woven polyester matt - but just can't think of the name. They would be good as they would remain in place within the cavity while i fixed the lining and i don't think are susceptible to mould. I will use the Anticon that i have but its really a roof blanket that will not stay in a wall cavity - can do in short runs but certainly not a one man job.   

[mshed65]

Hi,

Just following up on the above in the event that it may help others down the track. 

I remembered the alternative insulation batt i mentioned previously - polyester wall batt - is a Higgins product. Bradford also make them (Polymax) but these are only available in 90mm so won't fit within a 64mm top hat and even an excessive squeeze if the shed uses 75mm top hats. Like most building products, the various insulation batt materials have pros and cons.

Polyester batts pro's: not susceptible to condensation/moisture absorption and mould so not required to isolate from the cladding (which is required if using glasswool), quite stiff so will stay in place during lining installation and will not slump over time (as glasswool will if not tightly in the wall cavity), better sound insulation, no itchiness during installation. The cons, over standard glasswool batts, is lower R-value (resistance to heat flow or measure of insulation) and slightly more expensive. Having lower insulation properties for more $ generally means they are not the common choice for wall insulation. Generally only use when other factors come into play (such as here).

I though i should also clarify my comment on Foilboards not being great to fix ply sheets over. The context of this comment was if you were to fix the foilboards to the inside of the wall girts, spanning between them, and then have to fix the ply sheets on top of the foilboards. This is the preferred method of installation but of course you can install the foilboards directly to the wall sheeting and so they can sit within the cavity created by the girts (64mm or 75mm). You just have to create an airgap between the wall sheeting and foilboard with styrene spacer blocks or spacers made with the foilboard offcuts. The spacers can be glued to the wall sheeting and the foilboard glued in turn to the spacers. Both can be glued with construction adhesive or roofing silicone. I did consider this but the cost of boards, joining tape, and glue/silicone works out quite a bit more than the polyester batts. I would use this solution (and have done for a friends shed) if insulation was the most important and the foilboard was to be the finished inside wall surface. You can do the roof surface this way as well if the purlin spacing does not allow direct fixing of the foilboard but is a trickier job for one person - i am building on my own and this often dictates materials and methods used (fine if you could get hold of some painters trestles and plank). 

Dave, you asked "how waterproof is the floor?" As mentioned earlier some areas will be display areas and others a workshop so the floor will remain as a bare slab. I didn't pour the slab so don't know whether a vapour barrier was put down but not concerned as i am not going to tile or carpet. The top surface is quite waterproof as I have sealed the slab with a solvent based acrylic sealant - as i deemed this the best for my particular requirements. The concrete sealant decision whether to use a penetrating sealant (siloxine, silane, siliconate) or non-penetrating sealant (epoxy, acrylic, polyurethane) or even which one within these families, depends on many things and best discussed in a separate thread. Happy to discuss and help people decide if desired.       

[Dave-1]

Afternoon @mshed65 

Thank you for the info I do like your resoning. 

Would love to see the project whichever way you decide plus your reasonings. (I get confused with the "git sizing" need to look up what git is tho I suspect its to do with the roof?)

The reason I asked about the foor wasnt for waterproofing but more along the lines of water touching the edge of the walls you intend to put in and the insulation that may be low. 

I really like the information you have supplied. I will help others on the same path as you said. I dont have a shed tho one day would like to build a "windowed" outside room/greenhouse with a floor. So any of this information is good for me

Dave

[mshed65]

No worries Dave.

Sorry about the terms - i am an engineer so have to be mindful of using terms that are 2nd nature to me but not as familiar to others.

With regard to steel framed buildings, like Bunnings (ha ha), the roof framing that supports the roof sheeting are 'purlins' and the framing that supports the wall sheeting are 'girts'. 

When you plan to build your outside greenhouse, happy to discuss.

Marty

[Dave-1]

hahahhaha @mshed65 

Want to know how many times I walk around looking at the underside of roofs especially in large buildings? All the time and the Bunnings example is perfect! I knew purlins but not girts and yeah I am a sparky who dabbles in the building side

Thank you

Dave

[bowmatty]

Hi Dave, panels seem to be holding apart from 2, they will need an extra but of glue. Other than the two, they are holding pretty well. 
Since being insulated, no condensation is present and my deck area lounge has been drip free