Advice needed regarding repair of Steel Shed Roof

[RoyG]

Greetings,

I was noseying around the shed yesterday looking for the source of some water leaks (first decent rain in four months, and it poured into the shed !) and I got a nasty surprise. Water has apparently been leaking down around the roof sheet screws and onto the top of the steel purlins, probably for many more years than I've lived here, and as a result some of the purlins are pretty badly rusted out.

In places I can poke a screwdriver right through the rust. It scares the hell out of me to think that I was walking on this roof only 6 months ago. My guess is that the shed is roughly fourty years old, and looks might it may have been designed by Heath Robinson on one of his good days, using a fair quantity of recycled steel. Apart from the rusty purlins, the shed is very solid (over-built) and has stood up to a good few cyclones over it's life so far. The purlins are rectangular section steel box section roughly 70mm x 25mm x 2.5mm walls - not galvanised. I'm expecting that once the steel roof panels have been lifted, that I'll find that the steel roof sheeting will also be rusty where it has been resting on the rusty purlins.

So, I've decided that if I'm going to have to go as far as completely removing the old steel roof sheets, then I may as well take the opportunity to insulate the shed roof as it has always been very condensation prone, and stinking hot whenever the outside temperature goes much over 33 degrees. Considering that we get many days over summer where we exceed 40 degrees, it results in four or five months a year when it is impossible to work in the shed after about 11:00am on the hot days.

I've previously looked at various forms of insulation under the roof panels (e.g. Silisation or Kingspan AirCell, plus Fibreglass Batts, plus a ceiling to hold the batts up), but as it's a skillion roof sitting on rafters that don't lend themselves to having an ceiling attached to the steel rafters, I've always come up against brick walls when trying to design an insulation solution - especially as my goal is to have the temperature inside the shed remain below around 33 degrees on the hotest days, if at all possible.

MonoPane.jpg Since I now have to replace the existing steel roof sheeting, one option I'm looking at are these steel roofing sheet products that have insulation bonded to them. There are a few brands around. They all seem to be similar construction. A top sheet of coro or trim deck style ColourBond steel, bonded to a layer of foam insulation ranging between 25mm and 100mm thick (insulation thickness varies a lot between brands) and with another layer of flat ColourBond steel bonded to the underside. The underside layer of flat colourbond then becomes the shed ceiling when it's installed.

The image at right comes from the product brochure for a company called Superior Panel (they're reasonably local to me - about half way between Brisbane and the Gold Coast). Superior panel seem to use a 100mm layer of insulation - but so far I've found no specs for the insulation properties - I'll phone them on Monday. I also don't yet have any indication of cost.

Other companies such as Altek and ShadeMaster also have similar products, but their insulation layer is generally much thinner - in most cases 25mm. The Superior Panel mob seem to be focusing on domestic and commercial roofs, whilst I think Altek and ShadeMaster are focusing on the Patio Roof market.

So - my question. Does anyone have any experience with these Insulated Metal Roofing products ?

Regards,

Roy

[BobL]

I looked seriously at some of the insulated panel type products for both the walls and roof structure of my new shed but I was put off by the price at the time - maybe things have changed in 4 years. My understanding of those products is that they are useful for roofs designed to have wider spacings between everything ( I seem to remember some would span ~6m?) so fewer posts, joists and perlins can be used and you recover some of the cost this way. However, I wanted a shed with a strong roof frame and narrow spaced joists that I could support things from and store stuff in. I think you will find that if you already have a solid joist spacing that it will be less expensive to use a mesh and regular insulation.

[artme]

Bob's comments concerning the use of the roof space for hanging and storage are a good point.

I have a patio roof made from coolroom paneling. It is so cool under there that If I were to build a house AND had the money I would go for this same type of product. I would however choose a corrugated form.

The 75mm thickness certainly helps in terms of cooling and strength. My span is about 3meters and it is possible to walk on it without any problems.

[RoyG]

I have a patio roof made from coolroom paneling. It is so cool under there that if I were to build a house AND had the money, I would go for this same type of product. I would however choose a corrugated form.

The 75mm thickness certainly helps in terms of cooling and strength. My span is about 3meters and it is possible to walk on it without any problems.

Thanks for that info Artme - exactly the sort of information that I was looking for. I hadn't thought of cold room panels..... But as you say, corrogated or otherwise would be better than the flat urface cold room panels, but the insulation effect should be the same.

Does the insulation dampen the noise from rain etc on the steel roof ?

I spoke to a supplier/installer this morning. I'm expecting to get some indicative pricing on the material today, and a quote for repairs to the rusty purlins and supply and installation of the insulated roof sheeting later this week.

Discussions with the salesman this morning suggest that although the insulated roof sheeting is more expensive than plain Colourbond, he suggests that as you are avoiding the extra cost of the under roof insulation material, and the associated labour costs for installing the under roof insulation, that the total cost of supplying and installing the insulated roof sheeting is similar to the cost of supplying and installing a plain colourbond roof, plus under roof sisilation, plus under roof insulation, plus a structure to support the insulation. How true that statement is remains to be seen when I receive his installation quote later this week - I hope it is not just sales talk.

The idea of being able to store materials in the rafter space is appealing, but not really a practical consideration for me. I tore some tendons in my shoulders in an accident a few years ago, and as a result can't lift my arms above shoulder height, so the space in the rafters is not much use to me for storage.

I much rather like the idea of the smooth white ceiling provided by the underside of the insulated roof material. My fluros are suspended from the rafters. The white ceiling should reflect a lot more light down into the workshop, and make for a much brighter workspace.

Anyway, thanks for the input. Much appreciated.

Regards,

Roy

[artme]

Yes Roy, noise dampening is another benefit if you are looking for that. I rather like the sound of rain on an iron roof so it doesn't bother me.

Just make sure your installer uses the proper length screws with the large domed neoprene seals.

[nrb]

Have you considered the option of spray foam,had this done under my floor,great result.
My BIL raises chickens and his shed are done this way.

[BobL]

. . . .Discussions with the salesman this morning suggest that although the insulated roof sheeting is more expensive than plain Colourbond, he suggests that as you are avoiding the extra cost of the under roof insulation material, and the associated labour costs for installing the under roof insulation, that the total cost of supplying and installing the insulated roof sheeting is similar to the cost of supplying and installing a plain colourbond roof, plus under roof sisilation, plus under roof insulation, plus a structure to support the insulation. How true that statement is remains to be seen when I receive his installation quote later this week - I hope it is not just sales talk.

I considered adding extra under roof insulation but I found the sisalation by itself does such a great job in my 42 m² shed that a small in wall air conditioner can easily hold the shed indefinitely at a very comfortable temperature, even when its 42º outside.

Are your walls insulated/lined? If not I'd be looking to do that before adding more under roof insulation.

[rod1949]

I used the 50mm thick panels for a trailer I made https://www.woodworkforums.com/f184/flat-top-trailer-bush-145855

I brought it from Bondor http://www.bondor.com.au/ factory direct here in WA.

[artme]

My deck roof was bought from Bondor, but as I said it is coolroom paneling.