My render

[jack]

I have the same build system as @Bitpipe.

 

When the contractor who we engaged to put up backing boards (and install brick slips onto them) turned up for their first morning onsite, they realised that the studs behind the panelvent weren't spaced at convenient 400 centres. No idea how they'd missed that when pricing the job, since it was pretty clear.

 

One possibility was to cut the boards so that they fit the spacing that was there, but that was going to be a mammoth task. Probably more than 80% of the boards would have needed some form of cutting. 

 

In the end, we decided to go with counterbattens. Vertical battens were installed along the stud lines, then horizontal battens were installed on top of those. Fixings for the horizontal battens go through both battens and into the stud behind the panelvent.

 

I do have some concerns about the potential longevity of this approach. There's the odd bit of fine cracking along the mortar lines of the brick slips, but other than that it's mostly held up for over five years. I think with some care it could potentially be an approach that would work with renderboard.

[Mr Punter]

The batten issue can be even worse if you have external insulation on a timber frame.  There is often nothing to fix to in the corners.  Counterbatten is the way forward.

[SuperJohnG]

3 hours ago, Bitpipe said:

 

Is there a fixing to OSB that will give you more mechanical purchase

Its a good question, @LA3222 was advised and used screws for his roof battens. There was guidance from the manufacturer that x amount of thread had to go into the insulation to provide the correct mechanical fixing for the roof battens. I'm thinking it may be the same here and ok.  You just want to ensure really there is no relative movement between the SIP panel and the battens but also ensuring the required mechanical grip is there, which this should do. 

[ProDave]

13 hours ago, Jason L said:

Sorry I don’t know anything about that, other than it was one of the photos the presentation showed of issues that is caused without movement joints.  What are your issues ? 

A few patches of the top coat render have blown.  As far as I know (not totally sure until the remedial work is done) the base coat is intact.  The affected areas don't coincide with any joints let alone expansion joints (we have none) and I am sure are not related to building movement (none noticed)

 

We will be doing the remedial work in the spring now.  Due to Covid, it has been impossible to get the suppliers rep to visit the site so see the problem.  I really really wanted that to happen.  The only "resolution" I have been offered is the plasterer will pay for the material and do the work FOC  but I would really want an answer of what went wrong so will try again in the spring to get the rep to visit before we start the repairs.

 

My biggest concern is the repair patches will be visible either by being a different colour or texture, but equally don't wnat to have to re do each of the 2 affected walls completely.

[Jason L]

1 hour ago, ProDave said:

A few patches of the top coat render have blown.  As far as I know (not totally sure until the remedial work is done) the base coat is intact.  The affected areas don't coincide with any joints let alone expansion joints (we have none) and I am sure are not related to building movement (none noticed)

 

We will be doing the remedial work in the spring now.  Due to Covid, it has been impossible to get the suppliers rep to visit the site so see the problem.  I really really wanted that to happen.  The only "resolution" I have been offered is the plasterer will pay for the material and do the work FOC  but I would really want an answer of what went wrong so will try again in the spring to get the rep to visit before we start the repairs.

 

My biggest concern is the repair patches will be visible either by being a different colour or texture, but equally don't wnat to have to re do each of the 2 affected walls completely.

yeah would imagine that repairs will be fairly visible.   I would be interested to know what the reason is for it when you get them back and find out.

[LA3222]

2 hours ago, SuperJohnG said:

Its a good question, @LA3222 was advised and used screws for his roof battens. There was guidance from the manufacturer that x amount of thread had to go into the insulation to provide the correct mechanical fixing for the roof battens. I'm thinking it may be the same here and ok.  You just want to ensure really there is no relative movement between the SIP panel and the battens but also ensuring the required mechanical grip is there, which this should do. 

Kingspan directed me to Ejot, when I spoke to their tech department they told me the length of fixing to use and offered up a couple of options. They had done all the 'pull-out' (can't recall the correct name) tests on their fixings in OSB panels and advised me accordingly.

 

I've mentioned on here before that I didn't rate their fixings because with the roof battens the heads kept chewing out. My opinion has somewhat changed now as I am several thousand screws in with adding insulation and battens to my interior walls and have had no issues whatsoever. The ones used outside were stainless steel and rubbish, I'm using carbon steel ones inside and they're great.

 

With regards to things like fixings, spacings etc you really need to speak to the necessary tech departments if only to put your own mind at rest that you are doing it 'right'.

[ProDave]

42 minutes ago, LA3222 said:

Kingspan directed me to Ejot, when I spoke to their tech department they told me the length of fixing to use and offered up a couple of options. They had done all the 'pull-out' (can't recall the correct name) tests on their fixings in OSB panels and advised me accordingly.

 

I used all Ejot screws anf the big plastic caps.  The screws were not the best with a habit of the head stripping, I ended up referring to them as etij screws.

[Jason L]

51 minutes ago, LA3222 said:

 

With regards to things like fixings, spacings etc you really need to speak to the necessary tech departments if only to put your own mind at rest that you are doing it 'right'.

my list of things to do has just got a bit longer ?

cheers will do

[LA3222]

10 minutes ago, ProDave said:

I used all Ejot screws anf the big plastic caps.  The screws were not the best with a habit of the head stripping, I ended up referring to them as etij screws.

I had the same issue with 90mm long stainless steel types, couldn't use an impact driver with them as it trashed the heads.

 

I've been using 110mm and 150mm long carbon steel ones inside and not once has the head stripped whilst using an impact driver and I've done a few thousand now ?‍♂️

[Pete]

I have the Parex thin coat render system on tender boards, longest run 27m with no expansion joints. T/f company had no joints in the frame and moisture resistant board company told me they had done longer runs without joints. Been on 3 years and no cracks yet! 

My boards are fitted on a batten which is held in place by 100mm s/s screws of which I pre drilled and then impact driver to secure. I had to leave a 3mm gap on all sides of my boards and they where put on brick pattern style

[Bitpipe]

4 hours ago, jack said:

I have the same build system as @Bitpipe.

 

When the contractor who we engaged to put up backing boards (and install brick slips onto them) turned up for their first morning onsite, they realised that the studs behind the panelvent weren't spaced at convenient 400 centres. No idea how they'd missed that when pricing the job, since it was pretty clear.

 

One possibility was to cut the boards so that they fit the spacing that was there, but that was going to be a mammoth task. Probably more than 80% of the boards would have needed some form of cutting. 

 

In the end, we decided to go with counterbattens. Vertical battens were installed along the stud lines, then horizontal battens were installed on top of those. Fixings for the horizontal battens go through both battens and into the stud behind the panelvent.

 

I do have some concerns about the potential longevity of this approach. There's the odd bit of fine cracking along the mortar lines of the brick slips, but other than that it's mostly held up for over five years. I think with some care it could potentially be an approach that would work with renderboard.

 

On reflection Jack this is what we should have requested. I'll bring it up at the site meeting today.

 

 

[SuperJohnG]

5 hours ago, Pete said:

I have the Parex thin coat render system on tender boards, longest run 27m with no expansion joints. T/f company had no joints in the frame and moisture resistant board company told me they had done longer runs without joints. Been on 3 years and no cracks yet! 

My boards are fitted on a batten which is held in place by 100mm s/s screws of which I pre drilled and then impact driver to secure. I had to leave a 3mm gap on all sides of my boards and they where put on brick pattern style

This is good to know. I'll have SIPS so no expansion joint. Then battens and then render board (knauff aquapanel). Did you just do 600 centres in the vertical battens? Which would pick up the studs and then suit a 2.4m board? 

 

When you mention the moisture resistant boards.  Do you mean the render boards? (Just so I know I'm mot missing a step here. 

[Pete]

7 hours ago, SuperJohnG said:

This is good to know. I'll have SIPS so no expansion joint. Then battens and then render board (knauff aquapanel). Did you just do 600 centres in the vertical battens? Which would pick up the studs and then suit a 2.4m board? 

 

When you mention the moisture resistant boards.  Do you mean the render boards? (Just so I know I'm mot missing a step here. 

Yes, 600 centres on vertical battens fixed into the structural part of the t/frame. The boards are called Moisture Resistant Boards which the Parex render was adhered to.