SIP v Closed panel timbeframe

auntymaggie

Hi.Looking at SIP or Closed panel (twin stud with service cavity) timberframe for a new build.Assuming all things are equal in the u-value stakes what are the pros and cons with these two construction types?

delfagio

I myself am building using SIP panel timber frame.

Pro's for SIP is definitely the U-Values that can be achieved in both the walls and roof, and the airtightness levels. Because everything is factory made and pretty much millimetre perfect, you get a highly airtight envelope. Assuming you ensure to tape around Windows and doors with airtight tape etc. It's a lot easier to make a SIP house airtight than compared to a block house. Less effort.

Also with SIPs you can get great storage space in attic or additional rooms without too much difficulty.

For me, I got my conduits for all my HRV ducts and electrical cables for sockets, switches, TV points etc all installed into the SIP panels themselves which made things a lit easier for both HRV installers and electricians plus it saved me building services cavities onto the SIP panels later.

mp31

delfagio wrote: »

I myself am building using SIP panel timber frame.

Pro's for SIP is definitely the U-Values that can be achieved in both the walls and roof, and the airtightness levels. Because everything is factory made and pretty much millimetre perfect, you get a highly airtight envelope. Assuming you ensure to tape around Windows and doors with airtight tape etc. It's a lot easier to make a SIP house airtight than compared to a block house. Less effort.

Also with SIPs you can get great storage space in attic or additional rooms without too much difficulty.

For me, I got my conduits for all my HRV ducts and electrical cables for sockets, switches, TV points etc all installed into the SIP panels themselves which made things a lit easier for both HRV installers and electricians plus it saved me building services cavities onto the SIP panels later.

Who is the SIP Panel supplier can I ask... I'm thinking of using SIP panels for a kitchen extension.

gooner99

Interesting with the services already in the SIP panels. So with SIPs is it best to have all services already in the panels prior to install and does adding services cause a problem if done on site?

Can you also PM me your SIP supplier details.

delfagio

Hi Gooner, I'll pm you the details now.

Yea for me and my wife that's what we choose to do after speaking with the SIP supplier. It also meant we had to basically know exactly where we where going to put every switch, socket, TV point, cooler, fridge etc before we even built the house. It took plenty of planning and predicting on me and my wife's behalf.

We tried to future proof as much as we could also with installing extra conduits where we possibly might use if we where to ever change layouts or add things later in years to come.

Thankfully we got everything 100% spot on for what and where we needed all switches and sockets. Also the SIP supplier got pretty much every conduit installed exactly where we asked to within a few millimetres.

Doing it this way by installing the conduits in the SIP panels does kind of restrict you in possibly changing things later on during the build or even in later year's. As mentioned it needs a lot of thinking out prior to even been built. But as I said you could add in extras to try cover you for things later.

Doing a service cavity would be probably a better solution as you can change things as you want during the 1st fix on site or even in the future, but as said thankfully it did work out well for us.

Calahonda52

delfagio wrote: »

I myself am building using SIP panel timber frame.

Pro's for SIP is definitely the U-Values that can be achieved in both the walls and roof, and the airtightness levels. Because everything is factory made and pretty much millimetre perfect, you get a highly airtight envelope. Assuming you ensure to tape around Windows and doors with airtight tape etc. It's a lot easier to make a SIP house airtight than compared to a block house. Less effort.

Also with SIPs you can get great storage space in attic or additional rooms without too much difficulty.

For me, I got my conduits for all my HRV ducts and electrical cables for sockets, switches, TV points etc all installed into the SIP panels themselves which made things a lit easier for both HRV installers and electricians plus it saved me building services cavities onto the SIP panels later.

Can you take us through the buildup of the wall from outside, and for things like the timer, snd HRV ducts what thickness, and also where are the ducts vis a vis the AT layer and the insulation.
Thanks

delfagio

Calahonda52 wrote:

Can you take us through the buildup of the wall from outside, and for things like the timer, snd HRV ducts what thickness, and also where are the ducts vis a vis the AT layer and the insulation. Thanks

Hey Calahonda,

Ok, so from outside to inside the build up is as follows:

- 20mm External render
- 100mm Solid 4" block on edge
- 50mm cavity
- 155mm SIP Panel - made up of 15mm OSB Board cavity side, then 130mm XPS Rigid Insulation then 15mm OSB Board internal side
- 65mm insulated plasterboard with Skim coat.

My HRV ducts are only within the internal walls on the 1st floor in order to get the ducts from the attic to the ground floor ceilings. There are no HRV ducts in the external walls of the building envelope. The ducts themselves vary between two main sizes which are 60mm x 115mm and 60mm x 150mm.

Basically the SIP supplier left a channel in the internal upstairs walls, which had an OSB panel over this channel on the front side of the wall. My HRV installers then unscrewed this panel off the wall, installed their HRV duct once it was connected in the attic and in the ground floor ceiling and then the OSB panel was screwed back onto the wall. Essentially hiding the HRV duct in the wall which meant I didn't have to loose any space in the upstairs rooms by boxing out the ducts. Worked out very well in the end for us.

By using SIP Panel construction, there is no AT layer such as a membrane layer normally fixed to the walls, overlapped and taped. This is because the SIP panels themselves act as the AT layer.

I tried where possible to not install many electrical conduits into the external walls of the building envelope because this would mean a fractional amount of less insulation but unfortunately there was no choice but to install a few conduits due to needing some sockets and switches on the external walls. However the conduits are only small at 25mm depth x 37mm wide. These are installed just behind the OSB Board on the internal side of the SIP Panel.

delfagio

Oh sorry that should be 125mm insulation not 130mm.

The internal walls are 130mm, which is made up of 15mm OSB board either side with 100mm XPS rigid insulation in between.

BryanF

Is it weird that block is the preferred outer leaf in a timber frame build ?

delfagio

Your probably right Bryan, in the likes of America, and other country's, even in England, they tend to clad with timber, or other materials.

It seems in Ireland we are slower to drift away from the block built aspect that we have always done

Not sure why, but for me the block outer leaf just seemed it would be stronger, more protective.....

gooner99

BryanF wrote: »

Is it weird that block is the preferred outer leaf in a timber frame build ?

Would it not be preferable in exposed areas of the west coast of Ireland to have a block outer leaf?

lownhard

BryanF wrote: »

Is it weird that block is the preferred outer leaf in a timber frame build ?

Start shopping around for insurance on a TF without masonry outerleaf and you will understand!

Doesn't make a lot of sense...but non-standard is not favoured by insurance companies

delfagio

lownhard wrote:

Start shopping around for insurance on a TF without masonry outerleaf and you will understand!

Good point about the insurance though.

lownhard wrote:

Doesn't make a lot of sense...but non-standard is not favoured by insurance companies

Very true, insurance companies don't like anything non-standard.

BryanF

lownhard wrote: »

non-standard is not favoured by insurance companies

Crazy isn't it!

homewardbound11

lownhard wrote: »

Start shopping around for insurance on a TF without masonry outerleaf and you will understand!

Doesn't make a lot of sense...but non-standard is not favoured by insurance companies

Exactly my problem. 5 years ago it was nigh on impossible to get without a block outer leaf.

delfagio

Also back to the original posters query, auntiemaggie, another pro for SIP verses Closed panels.

(1.) SIP panels are generally thinner than Closed Panels, this means less wall eating space into your rooms.

For example my wall build up on external walls is 370mm in total, including outer leaf block and the cavity and plasterboarding, skim coating internally etc..
When I seen closed panel companies at Self Build shows they offered panels anywhere from 180mm - 400mm. So you could be looking at overall thickness of external walls between 330mm - 550mm. Check what thickness of closed panels will achieve the U-Value you are looking for and compare with SIP Panels.

(2.) Insulation...in SIP Panels the insulation is Rigid usually XPS or similar, meaning the insulation will not sag or reduce in u-Value over time. Some closed panel systems use rolls of insulation which eventually over time will sag leaving sections of the walls without insulation, hence reducing the U-Value

Paul Kiernan

I've a couple of questions:

How does SIP compare pricewise with CP timber frame? How do both compare with standard timber frame and why not just use standard TF? I know the stud creates a cold bridge but with insulated plasterboard surely this is negligible?

Where does the structural support come from with SIP? I'm thinking of a load bearing external wall maybe 14' wide with a 10' sliding door in it leaving 2' of wall each side to support the load. With traditional TF these sections would be massively beefed up with extra studwork. What's the solution with SIP?

Thanks.

delfagio

In our house the back wall in large open plan area is 14.2m long, we have three large window area's in this. 1st is 2.6m wide, the 2nd is 3.4m wide and the 3rd is 3.2m wide. Not a lot of wall left after these openings but it was all designed to take loading

Structural steel elements were added into the SIP Panels themselves to support the loading.

delfagio

Also on your other comment Paul, when using SIP Panels they use a lot less studs than conventional TF houses or Closed Panel houses. So with SIPs you have pretty much a solid wall of rigid insulation and little studs breaking the insulation forming cold bridging spots. The roof is SIP Panels too, so essentially you have a box of insulation forming your house. Ours is an oven.....from February this year to the start of August before we poured our floor screeds the house was between 23 -30degrees. There was nights in March and April where it was always cold outside at nearly 3 - 7 degrees and once I would go into the house it was like Spain, mid to late 20s. No heating or HRV up and running yet, house isn't completed yet. So hopefully won't need heating much.

The strength of the SIPs comes from the panel itself acting as one unit and it's quite high in compressive strength as far as I am aware. Not 100% sure on this one. Well my house hasn't fallen down yet ha ha plus I'm after adding about 12Tn of weight onto the 1st floor now from the liquid screed floor so it's still standing.......

nantony98

Why would you use insulated plaster board inside rather than get thicker sips in the first place?

delfagio

Price, I suppose, and the fact that I had to install plasterboarding anyway onto the SIP Panels, so we just went with 62.5mm insulated plasterboarding