Real World SIPs Experiences

[LA3222]

Just now, Dreadnaught said:

 

500 years isn't too bad going, at least for about half of the ship  

I wondered who would be the first to say it's reasonably well preserved all things considered.

 

Don't know why the Mary Rose popped into my head, but I liked it and went with it?

 

I may need to take the Mary Rose approach and just permanently submerge my soleplate and not expose it to air....maybe that will work?

 

If my soleplate lasts 100 yrs I'm ok with that....not my problem then....unless the secret to immortality is discovered?

[Dreadnaught]

9 minutes ago, LA3222 said:

I wondered who would be the first to say it's reasonably well preserved all things considered.

 

Its a wonderful exhibition down at the Portsmouth Historic Dockyard. Well worth a visit. I was last there just before they finished the treatment of the woodwork with polyethylene glycol so the ship was still covered with hoses and other contraptions. Keen to go back now all the pipework has been removed.

 

As my nom-de-plume suggests, I have an affinity for old historic ships and all things Royal Navy  

Edited February 19, 2019 by Dreadnaught

[Jeremy Harris]

Worth looking at this thread:

 

 

and this one archived from Ebuild:

 

https://web.archive.org/web/20171227081506/http://www.ebuild.co.uk/topic/15950-kingspan-tek-sips-panels/

 

[oranjeboom]

4 hours ago, PeterW said:

 

Is it just me that looks at the use of a ratchet strap as a way of holding a panel to a scaffold pole slightly scary ..??!!

I've had to keep the pole and strap in place ever since, otherwise the panels will all just tumble like a house of cards.

 

I think the strap approach is pretty standard - just a way to get the panels as tight as possible whilst the glue sets and the remaining panels are fixed/gunned.

 

4 hours ago, Mr Punter said:

Or these bits (and I have certainly done far worse):

 

 

It's fine, he was wearing a padded baseball cap and steel capped boots.

 

18 minutes ago, LA3222 said:

That's pretty much the point I'm making - the manufacturers do it one way yet you read self build forums and are left thinking the sole plate is going to rot like the Mary Rose and the house will collapse!!

 

Why the disparity in thinking?

 

If they will provide a warranty that covers the sole for 25yrs then most people would not bother with sole plate protection. However, how many companies would actually cover the sole plate specifically? And there are at least a few SIP companies that have gone bust. No good if the warranty went down with the company. 

 

Historic timber buildings with sole plates often require remediation work - why take the risk with SIPs? And I suspect SIP companies don't consider it to be an issue ( as most are fairly new with the method) and if building regs are happy that there is a DPC, then all boxes are ticked.

 

6 hours ago, LA3222 said:

Did you have any push back from the SIP company regarding the sole plate sitting on marmox?  One company I'm talking to want a dense block underneath it as a stronger medium for the fixings to go into.

 

Company I dealt with did not give a hoot what I used. I suspect most SIPs companies don't know what marmox blocks are and simply state that dense blocks would be best because they know what they are. No reason not to use them - just a matter of knowing how to use them and how to fix through them into the sole plate. Certainly not the first time marmox has been used on a SIP build, and as long as your BCO is happy with the approach why not? I did have to explain to her what they were etc, but she was fine. In many ways, the UK building industry is many years behind what is being done in Europe and the rest of the world ("well this is how we have done it in the past"). 

[LA3222]

@oranjeboom I'm not saying 'don't insulate the soleplate', I'm trying to get my head around why industry don't recognise it as the issue that self builders believe?  I think some of the bigger SIP companies have been operating in the UK for a long enough time now to have looked into this?

 

Thanks for the link @JSHarris, I knew rebuild was no longer accessible - didn't think about archives!

 

One issue I see cropping up is the presence of timber studs within SIP creating cold bridges.  I acknowledge this to be true, but then don't all TF have studs at 600 centres creating cold bridges (except Larson Truss, I Joists etc) so I don't see this as an issue (I may be wrong in this regard) as it surely performs better than standard TF?

 

The sole plate being cold seems to crop up a lot.  As I see it, this is a problem for anyone building in timber who doesn't use an Insulated Raft foundation? rather than a 'SIPs problem'. 

 

So from the threads I have seen, if you don't have an Insulated Raft foundation, the way to keep a TF (I say TF as this problem applies to a standard TF as much as it does SIP?) sole plate as warm as possible is to sit it on a marmox block and wrapped in insulation inside and out?

 

On another note, when I mentioned marmox blocks to one of the companies I am in talks with they didn't seem keen.  Concerns about the ability of marmox blocks to resist lateral loads?  The marmox website shows it as being suitable for under sole plates?

 

I appreciate the discussion - it helps to focus the mind somewhat.

 

Ta

 

Jamie

 

 

 

 

[Jeremy Harris]

The specific challenge with SIPs is because the "sole plate" is loaded in compression at both the inside and outside edges, because it's only the skins of SIPs panels that are load bearing.  This means that the outer edge of a SIPs panel needs to bear on the foundation, which isn't the case for something like twin wall timber frame, or externally insulated timber frame, where the perimeter insulation around the foundation can be under the outer edge of the walls, so providing contiguous insulation all around the wall/floor joint.

 

Adding perimeter insulation around the outside of the wall/floor joint is one way to mitigate the condensation risk.  Adding structural insulation underneath is another way.

 

When we were looking at using SIPs my preferred way was to use the thinner 140mm panels, that only just meet building regs on their own, but add about 100mm of external insulation all around, extending down to meet the foundation perimeter insulation.  I spent a fair bit of time working on the details to get this to work (from a passive house standpoint).  I also had the design detail agreed (after some debate) with the SIPs manufacturer.  I was planning to use Steico wood fibre externally, covered with membrane, counter battened and then timber clad.  The overall performance, in terms of U value and decrement delay wouldn't have been much different from what we ended up with.  It was the cost, together with the poor responsiveness from the supplier, that stopped us going down this path.

[LA3222]

@JSHarris your mention of decrement delay reminded me that I had a query there.  I know that with blown cellulose you have a rather large D.D.  When I crunched the numbers with my intended wall build up I had a figure of just under 12hours - this seems more than enough to me or am I looking at this wrong?  With 12hrs, by time house temperature twitches it will cool down outside?

[Jeremy Harris]

12 hours is fine.   The aim is to try to iron out the peaks and troughs of external temperature that occur between day and night, so that by the time heat from the sun (for example) has reached almost to the inside face, the outside has cooled down again so that that heat can flow back outwards.  The same applies when heat is flowing out of the structure during a cold night.

[LA3222]

10 minutes ago, JSHarris said:

12 hours is fine. 

So that's one thing not to worry about.  I'm happy with SIP in general,  I think I am inclined to add a VCL despite what suppliers state.  The foundation is yet to be decided but it seems that as I am likely having strip foundations it will require some careful attention.