Taping joins

[Mandana]

Has anyone done this themselves? How hard is it to do? We have double height areas in lots of the house so we will need a tower, but we’re trying to keep costs down by doing what we can ourselves. 
 

Also, how did you work out how much you needed? Our architect says we need Gawler tape, 60mm x 25m. 

[ProDave]

It this taping plasterboard, as in taping and filling the joints rather than skimming?

 

Have not heard of Gawler tape.

 

A scaffold tower on wheels sounds like what you want, always handy for maintenance and painting so probably worth buying one.

[Mandana]

4 minutes ago, ProDave said:

It this taping plasterboard, as in taping and filling the joints rather than skimming?

 

Have not heard of Gawler tape.

 

A scaffold tower on wheels sounds like what you want, always handy for maintenance and painting so probably worth buying one.

Hi Dave

 

No, it’s taping the joins where the SIPs walls meet the roof, all the corners and all the joins from SIP to beams. Once that’s done all exterior walls and ceilings will need membrane, then battening and plasterboard/plastering. 

[nod]

I’ve two tapers work for me full time 

I wouldn’t advise anyone to tape a full house out Your going to be looking at it for a long time 

A five bed house is only a couple of days work for two tapers 

Then a day to sand and spray a top coat 

[ProDave]

Ah you mean air tight taping of the joints.

 

I don't know the tape you mention but I used Tescon Vana, and another popular take is Siga Sicral.

[Mandana]

5 minutes ago, nod said:

I’ve two tapers work for me full time 

I wouldn’t advise anyone to tape a full house out Your going to be looking at it for a long time 

A five bed house is only a couple of days work for two tapers 

Then a day to sand and spray a top coat 

Sand and spray top coat? What’s that?! 

[Mandana]

Just now, ProDave said:

Ah you mean air tight taping of the joints.

 

I don't know the tape you mention but I used Tescon Vana, and another popular take is Siga Sicral.

Yes! That’s what I meant! 
 

Thanks for the other tape names. The Gawler one is what our architect recommended for our SIPs

[LA3222]

28 minutes ago, Mandana said:

Sand and spray top coat? What’s that?! 

Ha, there's some wires crossed here - @nod is a plasterer I believe so he is referring to the plastering part of the build whilst you are talking air tightness.

 

my build is SIP, I (the wife!) Is currently running a bead of silicone over every single seam that is an outside face of the house and then putting silver foil tape over it.

 

Next layer is 70mm of kingspan which again will have the seams taped with foil tape (no silicone).

 

Next layer is the airtight membrane, using Intello Pro Clima +. And i will probably use their tapes.

 

No particular reason for this approach, like most of my build im making it up as I go along?‍♂️ 

 

My theory goes that each layer will make it slightly more airtight so the sum of the parts should give me a good airtightness score. Its not costing much in time to do this as I'm busy doing guttering and drainage whilst the missus plods away at it.

 

Also, buy a scaff tower. I bought a zarges one for about £800 - a lot but with all the vaulted ceilings it will pay dividends to 'own' rather than hire. 

Edited August 13, 2020 by LA3222

[nod]

I’ve two tapers work for me full time 

I wouldn’t advise anyone to tape a full house out Your going to be looking at it for a long time 

A five bed house is only a couple of days work for two tapers 

Then a day to sand and spray a top coat 

 

yes a I realized after I replied 

Need to read the whole post ?

 

[Mandana]

16 hours ago, LA3222 said:

Ha, there's some wires crossed here - @nod is a plasterer I believe so he is referring to the plastering part of the build whilst you are talking air tightness.

 

my build is SIP, I (the wife!) Is currently running a bead of silicone over every single seam that is an outside face of the house and then putting silver foil tape over it.

 

Next layer is 70mm of kingspan which again will have the seams taped with foil tape (no silicone).

 

Next layer is the airtight membrane, using Intello Pro Clima +. And i will probably use their tapes.

 

No particular reason for this approach, like most of my build im making it up as I go along?‍♂️ 

 

My theory goes that each layer will make it slightly more airtight so the sum of the parts should give me a good airtightness score. Its not costing much in time to do this as I'm busy doing guttering and drainage whilst the missus plods away at it.

 

Also, buy a scaff tower. I bought a zarges one for about £800 - a lot but with all the vaulted ceilings it will pay dividends to 'own' rather than hire. 

Wow, that’s a lot of sealing!! We’d not thought about siliconing first. I like siliconing, but not at those great heights!! 
 

We’ll definitely need a tower. Thanks for your recommendation. I’ll look it up. 

[eandg]

How did you get on? Tape both externally (different take needed?) and internally? Any other SIPs kitters taped their joins?

[SuperJohnG]

18 minutes ago, eandg said:

How did you get on? Tape both externally (different take needed?) and internally? Any other SIPs kitters taped their joins?

I'll be doing it. Kit goes up in May, then once I get sorted I'll tape internally myself. Unsure if I'll bother with VCL at this point. 

 

Didn't think it was required externally. 

Edited April 15, 2021 by SuperJohnG

[Mandana]

1 hour ago, eandg said:

How did you get on? Tape both externally (different take needed?) and internally? Any other SIPs kitters taped their joins?

We ended up taping every join on every board, VCL on every single exterior SIP and that taped as well. 
 

Our prelim airtightness test result was 2.65 before boarding. We fully expect to be <1 when we’re complete. Well worth the time and expense of taping IMHO. 

 

Have to say the taping and VCL seems like a lifetime ago now though! 

[eandg]

7 hours ago, SuperJohnG said:

I'll be doing it. Kit goes up in May, then once I get sorted I'll tape internally myself. Unsure if I'll bother with VCL at this point. 

 

Didn't think it was required externally. 

 

I suppose if the tape works on the inside join then you don't need it outside. Belts and braces approach suggests to do it but there's a time and cost impact too. I've read that you don't need a VCL if you have MVHR. We're putting additional insulation in so makes sense to get the foil faced stuff and do it however. 

 

5 hours ago, Mandana said:

We ended up taping every join on every board, VCL on every single exterior SIP and that taped as well. 
 

Our prelim airtightness test result was 2.65 before boarding. We fully expect to be <1 when we’re complete. Well worth the time and expense of taping IMHO. 

 

Have to say the taping and VCL seems like a lifetime ago now though! 

Definitely sounds like a fit and forget type job. Now go work out how much tape required!

[Iceverge]

2 hours ago, eandg said:

 

I suppose if the tape works on the inside join then you don't need it outside. Belts and braces approach suggests to do it but there's a time and cost impact too. I've read that you don't need a VCL if you have MVHR. We're putting additional insulation in so makes sense to get the foil faced stuff and do it however. 

 

Definitely sounds like a fit and forget type job. Now go work out how much tape required!

 Caution using multiple airtightness/VCL layers. It's not a reliable way of getting a good blowerdoor score as you'll lightly 

 get the result that corresponds to your best layer only and the others will be redundant. 

 

In doing it you will increase your chance of trapping moisture in the wall with all the associated ramifications. Your cost of materials and labour will increase too.

 

You need a good air tightness layer somewhere in the structure of the wall. Normally in this neck of the woods that's placed towards the interior of the majority of the insulation. That means that you need a windtightness layer to the exterior of the insulation if it is of a permeable type to avoid wind blowing through it. Less of a issue with SIPS EPS etc. 

 

What is your wall buildup?

[eandg]

22 minutes ago, Iceverge said:

 Caution using multiple airtightness/VCL layers. It's not a reliable way of getting a good blowerdoor score as you'll lightly 

 get the result that corresponds to your best layer only and the others will be redundant. 

 

In doing it you will increase your chance of trapping moisture in the wall with all the associated ramifications. Your cost of materials and labour will increase too.

 

You need a good air tightness layer somewhere in the structure of the wall. Normally in this neck of the woods that's placed towards the interior of the majority of the insulation. That means that you need a windtightness layer to the exterior of the insulation if it is of a permeable type to avoid wind blowing through it. Less of a issue with SIPS EPS etc. 

 

What is your wall buildup?

 

140mm Kingspan Tek SIPS, 50mm Kingspan Thermowall (with foil facing), service cavity and 12.5mm plasterboard. Plan is/was to tape the joins on the kit, screw on additional insulation then tape the joins there. And potentially also to tape the joins on the external weatherproof membrane. 

[Iceverge]

Sounds fine. 

 

If it was me I'd tape the kit externally first making sure your windows and all penetrations are sealed to the SIPS. 

 

Then make a DIY blowerdoor fan. Depressurise the House and check for leaks coming into the building and rectify.

 

This will assure your windtight layer.

 

Then apply the external membrane, no need to tape. The membrane will be over the tape protecting them from any leaks that come through your cladding/rainscreen. 

 

Then apply the internal PIR. Tape all joints and tape the PIR to all penetrations and repeat your DIY blowerdoor depressurisation. This will assure your airtight/VCL layer. 

 

Doing this method will protect your structure from moisture and ensure that the wall performs to its designed parameters. 

 

[eandg]

11 minutes ago, Iceverge said:

Sounds fine. 

 

If it was me I'd tape the kit externally first making sure your windows and all penetrations are sealed to the SIPS. 

 

Then make a DIY blowerdoor fan. Depressurise the House and check for leaks coming into the building and rectify.

 

This will assure your windtight layer.

 

Then apply the external membrane, no need to tape. The membrane will be over the tape protecting them from any leaks that come through your cladding/rainscreen. 

 

Then apply the internal PIR. Tape all joints and tape the PIR to all penetrations and repeat your DIY blowerdoor depressurisation. This will assure your airtight/VCL layer. 

 

Doing this method will protect your structure from moisture and ensure that the wall performs to its designed parameters. 

 

 

Cheers - I'll see what the timeline is like for the installers (they finish by providing the external membrane but I suppose there's no reason I couldn't tape over a couple of nights before they do). I'll need to look into the DIY blowers and how to depressure the house but sounds like it's worth saving a day or two in the schedule for it. 

[SuperJohnG]

On 16/04/2021 at 11:26, eandg said:

 

Cheers - I'll see what the timeline is like for the installers (they finish by providing the external membrane but I suppose there's no reason I couldn't tape over a couple of nights before they do). I'll need to look into the DIY blowers and how to depressure the house but sounds like it's worth saving a day or two in the schedule for it. 

 ha @eandgI'd already commented on the thread for answers on. 

 

I think my solution might be to tape the GF/FF join as that's the biggest unsealable area internally then allow them to put the membrane on and just tape all internal joins.