Steel Structural Insulated Panels (SIPs) - anyone worked with them?

[windsock]

Looking at options for a small cabin build and have been considering the Steel Structural Insulated Panels (SIPs - often called Steel Sandwich Panels or Freezer Panels) as an option for the whole small (6m x 3.6m) structure.

Wondering if we have any designers or builders on the forum who've done anything with them in the past.

If no design/build experience, anyone lived in a building with these things in a cool/temperate climate?

[austastar]

Hi,
Youngest son is building with what he calls SIPs. But I think they are Structural Insulated Panels and skinned with a randomly spaced pressed plywood.
He was planning on using wood-fired hydronic floor heating, but dropped the idea after visiting his friend's SIPs house that didn't need additional heat in winter.
They are apparently very efficient thermal insulation.
Cheers .

[PhilipA]

Mate of mine made his trailer to carry his D type replica in.
They are heavy but that will not matter with a house. My main long term problem would be rust.
What about polystyrene bricks filled with concrete as has just been built near my house. That would be a good insulator and sound deadening.
Regards PhilipA

[windsock]

Hi,
Youngest son is building with what he calls SIPs. But I think they are Structural Insulated Panels and skinned with a randomly spaced pressed plywood.
He was planning on using wood-fired hydronic floor heating, but dropped the idea after visiting his friend's SIPs house that didn't need additional heat in winter.
They are apparently very efficient thermal insulation.
Cheers .

Yep, SIPs are catching on in this part of the world. Quick builds and energy efficient. There are two key types of SIPs. The one you have seen are comprised of Oriented Strand Board (OSB ) sandwiching expanded polystyrene (EPS). Very strong, and over here in NZ OSB SIPs are on a par or slightly higher cost-wise to the normal stick-build costs. I looked at these but you end up cladding the exterior as the OSB was not suited to long-term weather exposure.

The ones I am looking at are made with galvanised steel sheeting 0.59mm thick in colour-steel colours. Aluminium joinery for fixing each panel to the others. Weight is slightly lower than OSB and there is no need to place exterior cladding on it once built although I have seen people do so. Weight of 100mm Steel SIPS is 12.3 kg/m2 and for 150mm is 13.1 kg/m2. R-values are 100mm thick R2.62 and for 150mm are 3.62. Both these numbers are higher than our minimum levels in the NZ Build Code.

[windsock]

Mate of mine made his trailer to carry his D type replica in.
They are heavy but that will not matter with a house. My main long term problem would be rust.
What about polystyrene bricks filled with concrete as has just been built near my house. That would be a good insulator and sound deadening.
Regards PhilipA

G'day Philip,

Concrete and polystyrene sounds interesting. One option I am looking at is once a floor is in, setting up a couple of layers of concrete pavers inside and then placing some form of thin sheeting over them for thermal mass for gathering winter solar heat. I haven't quite thought things through yet how to finish the floor to an acceptable level while also still having the pavers heat up in the winter sun. I could just lay a raft of concrete on the final floor and polish this up but I would eventually like the option of trucking the whole cabin off-site once I am done with it. A trombe wall with thermal mass at the base could also be an option for solar heating. No concrete inside then.

Yeah rust worries me too a bit. Moisture control is a key to it I think. Painting cut edges is something I would consider necessary. Use of good sealant in the joints but also make sure moisture can leak out if it does get in there. I am sure there are tricks to it hence my question and posting. Breaking any thermal bridging looks to be a key part of design to avoid condensation. I have found a few diagrams online that are proving very useful.

The key reason I am looking at the steel SIPs is that the build could be temporary (about a few years [bighmmm]) and if I make them on a steel framework of bearers and joists on a conventional wooden piles arrangement I can lift them onto a truck with a hiab and haul them out of the place once I am done with them.

[V8Ian]

I'd be concerned about galvanic corrosion, Phil. Aluminum, zinc and steel. [bighmmm]

[loanrangie]

Don't these panels come in aluminium ?

[windsock]

I'd be concerned about galvanic corrosion, Phil. Aluminum, zinc and steel. [bighmmm]

Good point Ian. I think I need to look into this further. I see massive big cool stores made out of this stuff and have stood over 30 odd years now so I wonder how they deal with it or whether it is an issue or whether it is an issue that no one talks about.

Are there any fridgies on here that have seen any galvanic corrosion in cool stores made of this stuff?

[windsock]

Don't these panels come in aluminium ?

Yep, looked at them until I saw the price.

Products — ALSIPS (https://www.alsips.co.nz/products)

The price in the table in the "Weight and cost" section of this website for Steel SIPs is pretty well bang on (I have been quoted $54 per sqm of panel + GST) so can only assume the price for Ali SIPs is correct too.

[roverrescue]

Windsock
I have recently put up a small 16m2 Pavillion using Bondor SolarSpan panes which have 0.45 colourbond steel roof sheet, 100mm of polystyrene and an inner skin of smooth colourbond
This is what I think you are planning on using?

I have a bigger 50m2 carport to throw up using the panels in the next month or so.

As a roof structure these are pretty awesome.
Each sheet has a ridgelap on the roof sheet and a smaller lap for the ceiling. Each panel
Is 1m wide and my understanding is they can be had in 10m plus lengths. There is a wiring chase along the edge of each panel to run wiring etc into.

For a roof system there is pretty well established details for barges / fascia and guttering.

I can only assume brainiacs have worked out similar details when making an outside corner / soffit etc detail.

As you can span big distances I could see building a cabin with a very sparse light weight portal frame - using the panels as a simple gabled roof with large eaves and then screwing off panels horizonatally walls

It would go up super quick and at a guest door and window opening could be hashed in using simple timber framing albeit larger section sizes than perhaps normal internal joinery.


What size cabin are you looking to throw up

S

[windsock]

...using Bondor SolarSpan ... ...This is what I think you are planning on using?

Yes, sounds like a very similar product to what I have been looking at. I looked up SolarSpan and it appears an Australian product and does not appear on the Bondor NZ website. Unfortunate. I will have to ask them here if it is a product they do in NZ. I have seen a product made by MetalCraft here in Auckland that sounds like the same thing.

How did you find working with it in terms of tools? Did the panels come to your site needing any work for fitting or were they ready to go up? Most manufacturers here when I ask, indicate that they can cut to prescribed lengths but it is straight cuts only no angles so I would need to cut roof line angles and doors and windows and then seal and flash off as required. I have heard many options for cutting. I will be cutting off-site and transporting to site ready to go. No electricity or workshop on site yet.


For a roof system there is pretty well established details for barges / fascia and guttering.
I can only assume brainiacs have worked out similar details when making an outside corner / soffit etc detail.

Yep, I have been looking closely at some of the detailed drawings from both the manufacturers here. Over here anything that varies from the norm as indicated in the NZ Building Code has to be assessed by engineers as meeting the building code and it then given the status of "Acceptable Solution" followed by the clause of the code it is a solution to. Many of the panel manufacturers now are producing documents and specifications that depict acceptable solutions. I am very slowly understanding what needs to be done on my cabin plans.


What size cabin are you looking to throw up

At this stage I am looking at a single unit of 6m x 3.6m. I will likely get designs drawn and apply for consent for a second unit to bolt to the first at a future date.

[roverrescue]

Hi mate
As you mentioned panels delivered cut to length
The only cutting I had to do on the Pavillion was removing the roof sheet overlap of the first sheet so essentially a 4m long 60mm wide strip of roof sheet cutoff

For that cut I used nibblers so as not to burn up the sheet using a cut disc .

Essentially cuts are the same as any Tin roofing work and just hack out the polystyrene as needed.


My gut says for a 6x4 cabin the SIP could make an excellent simple roof and either skillion span the 4 or 6m dimension or you could make up a nice gable with an exposed timber beam on centre supported by gable walls.

The panels are great for their spanning and insulation ability - you can easily cut in down lights
BUT for a walking system my thoughts would turn towards something that is
A/ easier to fit out internally
B/ not steel sheeting internal - for a roof ceiling the smooth steel in surfmist white is pretty innocuous - but as a wall finish it is pretty industrial!!!

Will the canon be slab on ground or on piers?

What is your preferred flooring ?

S

[windsock]

[snip] For that cut I used nibblers so as not to burn up the sheet using a cut disc .

[snip]

My gut says for a 6x4 cabin the SIP could make an excellent simple roof and either skillion span the 4 or 6m dimension or you could make up a nice gable with an exposed timber beam on centre supported by gable walls.

[snip]

Will the canon be slab on ground or on piers?
What is your preferred flooring ?

Thanks for the replies. I had read somewhere by a manufacturer not to use abrasive discs as the sparks and heat causes a cavity under the sheet being cut. Makes sense. I have read of a steel cutting blade that goes on a circular saw and the depth of cut is set to only cut the steel skin. A cut is made on both sides where you require and then they used an electric hot-knife to cut and seal the polystyrene between the cut skins. Seems a long way of doing it. I am hoping there is a quicker way. Reciprocating saw is a thought. Any ideas? Want to minimise polystyrene blowing around in the wind.

Skillion roof of about 5 degrees and spanning the short dimension on each unit is the go in my current thinking. 300-400mm eaves on every side except the high end. This high side is where I will be joining the two modules. Each module is to have a skillion roof and then when eventually I have two units, they will be joined along the high side to form a simple gable roof.

Plywood floor over wooden joists supported by wooden or steel bearers on piles (Aus term is piers?) 600mm off the ground - insulated by expol polystyrene blocks and damp proof membrane. Wooden piles here on site would need to be approx 600mm into ground to reach the 100kPa soil needed for bearing pressures. Concrete placed around wooden piles. A pretty conventional suspended floor design in NZ. The whole idea is for a temporary set up for a few years and then when not needed the cabins can be unbolted and can be relocated on the property or transported off-site. Cabin dimensions reflect this so as to be readily lifted by a hiab or large digger.

[roverrescue]

Although your design lends itself to SIP
I wonder if looking into timber based SIP for the walls would make internal fitoff easier.

Cutting the metal panels will never be quick/ quiet or clean!!!

If you ran conventional stick walls , made them with double 90x45 studs , 200x45 LVL on face for top and bottom plates youd have plenty of cavity to insulate.

It would also be much simpler when the time came to join two cabins on the high side to install a big LVL and open up the joining wall.

You can still fire off colourbond sheets as external wall cladding if that’s the look you want and internal walls could be gyprock or plywood or whatever took your fancy

S

[scarry]

Are there any fridgies on here that have seen any galvanic corrosion in cool stores made of this stuff?

Yes,very bad corrosion,but it is usually near where it meets the concrete floor.

Insurance companies are right onto cold room panelling in buildings as well.Some buildings with the standard polystyrene sandwich panel cold rooms are actually uninsurable.

The fire rated panelling,different companies have different names for it is better,but insurance companies still don’t like it.

As an example,I know of a 1400m square tilt panel shed.
Insurance for the building was around $10K a year.
We installed 60% area of the shed into cold rooms,using the latest fire rated panelling,and the building insurance is now just over $25K.

[roverrescue]

Scarry

I have heard of fire issues in polystyrene panelling
But the Bondor panels appear to meet AUs code for bushfire safety both as walls and roofing
I’m no expert at bushfire regulations but can only go by the company certifications ?

http://bondor.com.au/sites/default/files/IGNS-7258%20I01R04%20Bondor%20Bushfire%20Advisory%20Not e%2030072019_10.pdf


When used as a roof, the finished panels with wrap around fascia and barges would appear to my eye to be pretty safe from ember attack (barring a gutter full of leaves?)

Steve

[rick130]

Scarry

I have heard of fire issues in polystyrene panelling
But the Bondor panels appear to meet AUs code for bushfire safety both as walls and roofing
I’m no expert at bushfire regulations but can only go by the company certifications ?

http://bondor.com.au/sites/default/files/IGNS-7258%20I01R04%20Bondor%20Bushfire%20Advisory%20Not e%2030072019_10.pdf


When used as a roof, the finished panels with wrap around fascia and barges would appear to my eye to be pretty safe from ember attack (barring a gutter full of leaves?)

SteveSteve, the big guys like Bondor only supply fire rated panel, I think you'll find that's all they make but some of the smaller suppliers, who knows?

As Paul said, the only spots you'll really see corrosion is where the panel is embedded in concrete with aluminum coving. Or the bare panel used as a floor in old restaurants. (Where it should have chequer plate over the top and sealed properly with silicon)

The rooms from over 30-40 years ago used an aluminum H section joiner and we never had an issue with corrosion, but the voids were filled with mastic for vapour sealing.
The new stuff is a tongue and groove design folded into the skin.
Obviously all the angles used in medium and low temp rooms still use aluminum angle, and aluminum rivets with a bucket load of non-setting mastic between.

[windsock]

Although your design lends itself to SIP
I wonder if looking into timber based SIP for the walls would make internal fitoff easier.

Good points Roverrescue. Internal fitout will be easy enough with light timber framed walls with the SIP-adjacent stud tek-screwed to the SIP or fixed by angles screwed to each adjacent surface. There are specifications from the manufacturer that show various methods.

The principal reason I am looking at SIPS is cost effectiveness. Light wood frames (conventional stick build) are more expensive than SIPs and far more labour intensive to erect due in part to a bureaucratic system administered by councils shy/nervous from an era of leaky homes liability issues. While I am comfortable with stick-builds and can do it, it is not considered at present due to cost and time constraints. Timber is stupid crazy prices here in NZ at the moment. We have a building boom driven by a housing shortage. Lead times for some materials is months. China is paying a premium for wood logs so many mills here have to pay the same premium prices just to get raw materials. Some milling places are going out of business through lack of raw material. Carter Holt Harvey, one of our biggest mills and supplier of wide-wood (joists and beams etc) has stated publicly it will cease supplying Bunnings, ITM and Mitre 10 and will only supply subsidiary merchants due to not being able to keep up with demand. Some real strange stuff happening in the market place at present for a country full of bloody pine trees.

As for subsequent joining of modules (cabins); strategically placed exterior doors become interior doors later [thumbsupbig] Design layout means I can later have either joined cabins or two free standing cabins with exterior doors fitted.

[rick130]

And for a dwelling all services will be exposed, all electrical will have to be run in conduit, etc etc.
That may increase the cost of finishing compared to a conventional build.

[windsock]

Yes,very bad corrosion,but it is usually near where it meets the concrete floor.

Yep, reading the spec table of compatible materials in the building code I'd need to watch out for water around surfaces where cement surfaces and aluminium can come into contact. Another thing I would need to watch is the use of Copper Chrome Arsenic (CCA) treated wood coming into contact with aluminium or galvanised surfaces and water.

I will add insurance issues to the things I need to do due diligence on.

[windsock]

And for a dwelling all services will be exposed, all electrical will have to be run in conduit, etc etc.
That may increase the cost of finishing compared to a conventional build.

Yep, good points. I want to avoid looking industrial if possible. If I cannot, then I will go whole-hog and have pipe bridges. However, in the design layout I am working on, all plumbing will be very short runs as the bathroom and kitchen are in adjacent rooms separated by a wooden partition wall and the services will come under the floor and up the inside of the wood frame or in the case of kitchen units, behind the kitchen unit. An gas califont water heater will be placed on the exterior wall adjacent to the kitchen and bathroom.

Wiring will be interesting. Currently working on what I need for that.

Thinking about placing floor to ceiling shelving units for storage in strategic places so if I combine this concept with conduit placement...

I may have a means of making it look less industrial... [biggrin] There are apparently wire chases incorporated into the SIPs wall panels so if I can predetermine placement, I can use these but that means I need to be more organised...

[roverrescue]

The Bondor panels have a wiring chase along every join
So 1m centres or there abouts

From talking to a sparky mate it is very little problem to drill a hole anywhere in the panel then drill/hack a channel to the chase and run wiring internal
To the panel. Obviously a little more fiddle than conventional wiring prior to finish but certainly not requiring external fixation.

My thoughts are that I wouldn’t “love” the feel of internal metal walls... ceiling in a cabin no problems

But walls would seem cold (even though it won’t be)

Steve

[rick130]

The Bondor panels have a wiring chase along every join
So 1m centres or there abouts

From talking to a sparky mate it is very little problem to drill a hole anywhere in the panel then drill/hack a channel to the chase and run wiring internal
To the panel. Obviously a little more fiddle than conventional wiring prior to finish but certainly not requiring external fixation.

My thoughts are that I wouldn’t “love” the feel of internal metal walls... ceiling in a cabin no problems

But walls would seem cold (even though it won’t be)

SteveCool, so quite different to coolroom panel

[loanrangie]

Cool, so quite different to coolroom panel

I assume that cool room panels wouldn't be considered structural since they are usually contained within a separate structure .

[scarry]

Generally,Bondor supply EPS,which is the standard type polystyrene panels that do have a fire retardant.
They also supply XFLAM,which is their range of fire resistant paneling,for cold/Freezer rooms, etc.
Both these are sandwiched between .4mm colour bond sheetmetal.

Its the fumes that come off the polystyrene,when burnt, which is the issue.

And we use Polyurethane sandwich panels at times as well, another Bondor product, but usually for floors of Cold/Freezers,due to its higher insulation properties.

The rooms I referred to in my earlier post were done in XFLAM,i had to look up the job as I couldn't remember what it was called[bighmmm]

[scarry]

Cool, so quite different to coolroom panel

yes, seems a completely different product.

I wonder what the Bondor insulation material is,Polystyrene(EPS)or something like the XFLAM product?

[windsock]

My thoughts are that I wouldn’t “love” the feel of internal metal walls... ceiling in a cabin no problems
But walls would seem cold (even though it won’t be)

Yep, I am with you there. I will have view windows on one side and floor to ceiling shelving out of varnished plywood about the place. I think I can minimise steel walls. In the kitchen area it'd be an OK feature I guess. The bedroom area is causing me thought. I could continue shelving in there but the thought of looking at all the bits and bobs that the wife would fill them with leaves me as cold as looking at steel walls. My fishing gear would only take up a few cubbyholes. Need more fishing gear. Mostly dark when I am in there so maybe won't be as bad as I think it could be. [bigwhistle]

[V8Ian]

Pictures, decorative mirrors, feature mural or ceiling to Florida drapes. How often do you stare at walls? There's plenty of way to trick the eye or deflect focus.

[windsock]

Fun with magnets! I have a pile of small neodymium magnets. [bigwhistle]

We have a heap of words on magnetised materials for a fridge. The wall is now the limit!

I can start collecting magnetic signs...[bighmmm]

[roverrescue]

Scarry


“I wonder what the Bondor insulation material is,Polystyrene(EPS)”

According to their website they use
EPS-FR (fire retardant) so who knows what it is chemically

S

[Gav 110]

I have wired rooms made of cool room panel before, a hot rod soon makes a suitable cable channel in the polystyrene, just make sure you install it in conduit or use the right type of cable
https://uploads.tapatalk-cdn.com/20210328/d5b0998ad89dbb47fa576eb9062d0e24.jpg

[emoji1531][emoji1531]

[Arapiles]

Check out the ATA website, I recall a house in Melbourne (possibly Brunswick) being built with coolroom SIPs. Interior looked metallic.

Either Sanctuary or Renew had an issue in the last year or so that focussed on SIPs for house building but largely the OSB and magnesium oxide ones.

I was keen to use the insulated and fire-resistant Colorbond sheets when we re-roofed our house but at the time we were told that they couldn’t be used on a gabled roof.

[scarry]

Scarry


“I wonder what the Bondor insulation material is,Polystyrene(EPS)”

According to their website they use
EPS-FR (fire retardant) so who knows what it is chemically

S

Standard,polystyrene,with fire retardant.Been around since Noah was a boy.Not the latest fire rated XFLAM.

Should be fine, just check insurance.

As someone said,right type of cables need to be used, or it needs to be in conduit.
I had to use that special cable for the downlights in the roof of our new deck as it was polystyrene sandwich panel, designed as roof panels.
You may find on the panels you are going to use, the wiring channels are separated from the polystyrene so normal cables will be fine.

Good luck with it all.

[windsock]

Thanks for the heads up on the plasticizer issues. I take it normal PVC conduit is fine it is just the particular PVC insulation that is the issue?

Is PVC-free insulated wiring generally available or is it considered an order-in item in the electrical industry?

[windsock]

Check out the ATA website, I recall a house in Melbourne (possibly Brunswick) being built with coolroom SIPs. Interior looked metallic.

Either Sanctuary or Renew had an issue in the last year or so that focussed on SIPs for house building but largely the OSB and magnesium oxide ones.

I was keen to use the insulated and fire-resistant Colorbond sheets when we re-roofed our house but at the time we were told that they couldn’t be used on a gabled roof.

Interesting that they said that about gabled roof. What angles are you talking about? I have seen a couple of diagrams indicating how it can be done to satisfy the NZ build code. Maybe these are NZ specific or have been developed for residential after the time you were looking. I know the ridge flashing needs to be designed to consider the wind zone the build is located in. In low angles, a wide band of adhesive is also used along the ridge prior to the ridge flashing going on.

[scarry]

Thanks for the heads up on the plasticizer issues. I take it normal PVC conduit is fine it is just the particular PVC insulation that is the issue?

Is PVC-free insulated wiring generally available or is it considered an order-in item in the electrical industry?

Order in at huge cost,did you expect anything else?[bigsad][thumbsupbig][biggrin]

The stuff we use has orange insulation.Luckily the sparkie we use does a bit at the local meat works so often has some hanging around.

[Arapiles]

Interesting that they said that about gabled roof. What angles are you talking about? I have seen a couple of diagrams indicating how it can be done to satisfy the NZ build code. Maybe these are NZ specific or have been developed for residential after the time you were looking. I know the ridge flashing needs to be designed to consider the wind zone the build is located in. In low angles, a wide band of adhesive is also used along the ridge prior to the ridge flashing going on.

About 10 years ago, but it seemed odd to me at the time.

[roverrescue]

I’ll check with my sparky re: PVC insulation and polystyrene
But reality is XLPE insulated wiring isn’t too hard to source (most PV wiring is this) And is not crazy $

Steve

[windsock]

I’ll check with my sparky re: PVC insulation and polystyrene
But reality is XLPE insulated wiring isn’t too hard to source (most PV wiring is this) And is not crazy $

Steve

Thanks, I'll have to ask around here too. I am planning on running a conventional 230V AC circuit but as it going to be an off-grid supply, I was also looking taking the opportunity to run a secondary 24V DC circuit in parallel in a few places where I might be able to run DC appliances and lighting.