Blogtastic!

[worldwidewebs]

12 minutes ago, Crofter said:

What type of membrane is on there? They do come in different grades and weights. Mine is not the cheapest stuff as I knew it was likely to remain exposed for quite some time. The biggest problem I had was the south gable which faces into the weather, and which I had not battened; the membrane started to tear slightly around some of the nail holes. In the end i just slapped a whole second layer on top, and then stuck the battens on, and it's been absolutely perfect since. I've had my chipboard flooring down for several months now- no way that I could have done that if the membranes were leaking.

 

Your flat roof might be difficult to keep waterproof though, I imagine the water will always pond and then seep through the nail/staple holes.

It's Ampatop Aero Plus - apparently quite expensive. 

 

I think on the flat roof it is coming in where two sheets of it are joined as the join itself doesn't seem the best but as I say, maybe it's just that it needs the final covering to be fully waterproof, but it does beg the question why bother with it if that's the case.

 

I pinged MBC an email over the weekend so I'm sure it'll be sorted in the next couple of days

 

[worldwidewebs]

I've popped up a new blog entry for those that are interested

https://selfbuildnoviceblog.wordpress.com

 

Slow progress now the MBC guys have left (I was warned) but at least it is progress of some sort!

 

As an aside, my brickie called me a couple of days ago and said he's starting the external blockwork that will support the stone cladding on Thursday next week. Which is good news aside from the fact that I haven't decided on where I want the external lights. This poses a problem as I need to fit some conduit in the timber frame though which I'll pass the cable and this must be done before the blockwork goes up. So a question to you all - what lighting do you suggest? Conduit going in this weekend...

 

[ProDave]

A light above or beside each door is all I would have personally, and perhaps one or 2 along the side if it's a passageway.

 

If you want to know the meaning of a slow building site, look at mine. It's over a year since i said farewell to my builders (amicably and only because I was running out of money so can't afford to pay labour)  It's taken me all of that year to get the outside of my house and plot finished, and only now am I starting to work on the inside.
 

[TerryE]

22 hours ago, worldwidewebs said:

This poses a problem as I need to fit some conduit in the timber frame though which I'll pass the cable and this must be done before the blockwork goes up.

 

You will need a long drill if you want to make this easy.  I used an old 1m × 15mm masonry bit.  If you are using 20mm tube then drill the hole on the inner; use the long drill in-to-out; withdraw the drill after doing the pilot hole and drill the outer hole from the outside using the pilot as a guide.  Then thread the drill back through the new enlarged outer hole.  Remove drill from the chuck and slide the pipe over it as a guide; push the pipe through and out to the outer wall line if nec.  Sikka tape both sides for air tightness.  Neaten outer after the stone skin is up;  foam and silicon after the cable is in to complete air tightness.  Takes about 10 min per hole with a bit of practice.

[worldwidewebs]

Thanks Terry, great advice. Just need to get my hands on some Sika tape as none was left when the guys vacated the site 

[worldwidewebs]

Well, the air-test was performed this afternoon and we achieved 0.27 air-changes per hour. BOOM! 

[Bitpipe]

21 minutes ago, worldwidewebs said:

Well, the air-test was performed this afternoon and we achieved 0.27 air-changes per hour. BOOM! 

 

Well done!  Is that a record for this site?

 

Was much taping required?

[worldwidewebs]

5 minutes ago, Bitpipe said:

 

Well done!  Is that a record for this site?

 

Was much taping required?

I know Darren has had better recently. He thought we'd get about 0.4 and we were all pretty amazed at the result, especially as we know the doors are leaking and need sorting out. 

 

I can't really comment on the amount of taping as I don't know what 'normal' might look like. I know I didn't do any extra work that I was planning on doing though

[Bitpipe]

Just now, worldwidewebs said:

I know Darren has had better recently. He thought we'd get about 0.4 and we were all pretty amazed at the result, especially as we know the doors are leaking and need sorting out. 

 

I can't really comment on the amount of taping as I don't know what 'normal' might look like. I know I didn't do any extra work that I was planning on doing though

 

I meant temp taping around doors, not the permanent variety

 

[worldwidewebs]

5 minutes ago, Bitpipe said:

 

I meant temp taping around doors, not the permanent variety

 

Ah, no none at all

[Jeremy Harris]

That's a damned good result!

 

Ours came in at 0.43 ACH at 50 Pa, without adjusting the doors, and no temporary taping around the doors either.  We had leaks at the French doors and the front door, but there was no time during the test for me to adjust them, as we'd met the required PassivHaus spec and the air test chap needed to get a move on to the next job.

 

I later did a very rough test, with my home made blower in the same window that was used for the proper air test, and set what I thought was about the right pressure (I didn't then have a calibrated low pressure sensor).  I adjusted the doors and sealed up the keyholes deep inside with some firm-setting grease, and, based on the change in flow rate, I reckon I dropped the leakage by around 40% to 50%.  As supplied the French doors were the biggest leaks by far, just because the two leaves weren't properly aligned, so the seal at the bottom centre wasn't really seating properly.

 

If I'd been around all the doors before the air test, and fixed the slight misalignment, I'm sure the result would be better.  I just didn't think about it at the time, though, and to be honest, once you get below the PH limit I think any real gain is going to be pretty small.  I was surprised at how big a leakage difference there was between a door being closed, and a door being closed and latched.  Ours don't seal at all well until they are latched into the locked position, I found.

[dogman]

Cracking result. Hope my MBC build is ias good

[Steptoe]

On 14/12/2016 at 20:30, TerryE said:

 

You will need a long drill if you want to make this easy.  I used an old 1m × 15mm masonry bit.  If you are using 20mm tube then drill the hole on the inner; use the long drill in-to-out; withdraw the drill after doing the pilot hole and drill the outer hole from the outside using the pilot as a guide.  Then thread the drill back through the new enlarged outer hole.  Remove drill from the chuck and slide the pipe over it as a guide; push the pipe through and out to the outer wall line if nec.  Sikka tape both sides for air tightness.  Neaten outer after the stone skin is up;  foam and silicon after the cable is in to complete air tightness.  Takes about 10 min per hole with a bit of practice.

do NOT foam and silicon the cables, unless you are absolutely certain it will have no detrimental effect on the cable, there is proper stuff to use, compound, there may be a proper non trade name for it, perhaps @ProDave or @Onoff will know it,

Most silicons and foams will 'eat' into the cable 

[Onoff]

1 hour ago, Steptoe said:

do NOT foam and silicon the cables, unless you are absolutely certain it will have no detrimental effect on the cable, there is proper stuff to use, compound, there may be a proper non trade name for it, perhaps @ProDave or @Onoff will know it,

Most silicons and foams will 'eat' into the cable 

 

Worms/can! 

 

Do you mean intumescent mastic?

 

Go for one that says specifically for cables like Rockwool FIREPRO - that's water based. I'd always dubious of stuff from "the pound shop" with a never heard of make that stinks to high heaven to boot and gives you a cheap high.

 

On the expanding foams, Soudafoam's FR deffo says for sealing of "cable" penetrations. Again a quality brand.

 

EPS beads or sheets sandwiching cables is the nasty one for T&E, to do with it drawing out plasticizers and making the cable brittle as well as gooey. I guess the same but to a lesser extent with SWA.

 

And don't forget if you seriously thermally insulate a cable over 0.5m with whatever, then you need to consider its current carrying capacity. If it is getting warm then it'll make it all the more likely to attack from some dubious "mastic".

 

Check out Wiska One Gel silicone based mastic that goes in a standard gun. Comes in a tube and is one part unlike their Magic Gel. Bumpf says it makes a  water, dirt and GAS so I'd assume "air" tight joint. RS do something similar under their own brand.

 

Then there's the fire "putties". Tbh air tightness is something I'm not over familiar with. With intumescents its just fill the hole up and you'll know it'll expand if there's a fire. Never worried before whether its air leaky beforehand!

[TerryE]

4 hours ago, Steptoe said:

do NOT foam and silicon the cables, unless you are absolutely certain it will have no detrimental effect on the cable, ... Most silicones and foams will 'eat' into the cable 

 

3 hours ago, Onoff said:

On the expanding foams, Soudafoam's FR deffo says for sealing of "cable" penetrations. Again a quality brand.

 

@Steptoe, I am not sure of the scientific basis of your assertion, or perhaps it's just an old street tale?  As Onoff says, many of the foams include this as one of their purposes.  I've got very few penetrations through the TF fabric; mainly exterior lights, etc.  All extremely low current in 1.5mm cable or bigger. 

[Onoff]

44 minutes ago, TerryE said:

 

 

@Steptoe, I am not sure of the scientific basis of your assertion, or perhaps it's just an old street tale?  As Onoff says, many of the foams include this as one of their purposes.  I've got very few penetrations through the TF fabric; mainly exterior lights, etc.  All extremely low current in 1.5mm cable or bigger. 

 

Go back a bit in time and there was definitely I'm sure issues with early PU boards and the pvc of T&E cable. PIR is as I understand more stable. Given that expanding foams are I think generally PU it's fair that a lot of people avoid them unless is says they're OK for cabling. Less of a worry too with new pvc cabling as the composition of that too I believe has changed so the plasticizers are less "migratory". 

Edited February 13, 2017 by Onoff
Spelling of plasticizers

[Steptoe]

1 hour ago, TerryE said:

 

 

@Steptoe, I am not sure of the scientific basis of your assertion, or perhaps it's just an old street tale?  As Onoff says, many of the foams include this as one of their purposes.  I've got very few penetrations through the TF fabric; mainly exterior lights, etc.  All extremely low current in 1.5mm cable or bigger. 

I've seen evidence of the leeching effect,

As long as the substance actually states its OK then I don't see any issue, but I wouldn't just use any random sealant.

I've seen newish T&E in a loft almost completely stripped by polystyrene bead type insulation,

In general I stick to using a standard type 'compound' ,

But if @Onoff reckons its still OK, then I'm sure it is,

And I'm sure @ProDave knows of more specific types for better properties at insulation etc most likely. 

It was just a general warning that not just any old expanding foam/silicon should be used in contact with PVC cables.