Think we have a builder

[CalvinHobbes]

So pleased, I think we have a guy who will do groundwork and help us manage the build with a good reputation.  

He appreciates our need to save money and said we could save a lot by making sure it's airtight ourselves. Presumably that means with the parge coat I read here?

So when and how do we do that? Will they build both walls at once? If do you just do outsides?

Edited February 19, 2023 by CalvinHobbes

[Nickfromwales]

Congrats.

What are you building with? Masonry ( brick and block / block and block ) ?

 

After the dazzle of getting a guy on board, remember to STILL have every nut and bolt in writing and a full scope of works in each of your possession(s). Keep this professional and formal at all times.

[CalvinHobbes]

Thanks, deffo that's good advice. 

Block and block. 

[CalvinHobbes]

We had a meeting with architect too and I asked was there anyway we could save money. The plans were for a zinc roof which came down partially at sides. I explained we were thinking of trocal, he said instead go for coated metal and we could paint the sides the same colour but keep the ends metal. I guess that means in the future we could get solar panels if it was metal?

[Nickfromwales]

Defo a parge coat then.

Airtightness is inside, and not outside. So when you stand inside each room, you're staring at the enemy.

Are you having a rim board and the joists then span off those, or has your architect not specified this yet? The worst option is to have them penetrate the internal block leaf and create pockets which breach the internal space to cavity.

 

9 minutes ago, CalvinHobbes said:

We had a meeting with architect too and I asked was there anyway we could save money. The plans were for a zinc roof which came down partially at sides. I explained we were thinking of trocal, he said instead go for coated metal and we could paint the sides the same colour but keep the ends metal. I guess that means in the future we could get solar panels if it was metal?

All depends if it is a standing seam metal, and if you have the structure designed to have capacity for 20-25kg/m2?

[nod]

Parge is a waste of time and money 

If you decide to use it Call it by what it says on the bags Sound block As it will encourage the Brickies and plasterers not to do there jobs properly 

 

Well done in securing groundwork’s 

Absolutely crucial in any build 

[Nickfromwales]

4 minutes ago, nod said:

Parge is a waste of time and money 

Depends on what is going on top? Dot n dab or full wet spread, me old china mug.  

[nod]

Just now, Nickfromwales said:

Depends on what is going on top? Dot n dab or full wet spread, me old china mug.  

Sorry Nick 

Your wrong 

Dot and dab can be made extremely airtight I’ve been doing this for forty plus years 

We use hundreds of bags of Parge each year Even the housing associations have stopped using it for airtightness Always for sound 

The only time I use it is on some self builds and I always tell my guys that it’s not for airtightness 

Making sure that the block work is pointed and bar jointed and around joists also 

15 plus years ago you could see into the cavity as the Brickies new we would come along and seal everything 

But that stopped overnight 

 

[Nickfromwales]

Just now, nod said:

Sorry Nick 

Your wrong 

Dot and dab can be made extremely airtight I’ve been doing this for forty plus years 

Didn't say you couldn't. However, I have assisted with airtightness on a Velox ICF build where the parge coat worked exceptionally well, because I made sure it was detailed meticulously. Passive Purple was applied where opposing faces met, in internal and external corners etc, plus anywhere that AT tape was to be applied. Big thanks to Adam White of Intelligent Membranes who came out to site and assisted.

On a different ICF job there was no parge done, but liquid membranes did go on, and that scored significantly worse.

 

Perhaps we are both right    Many ways to skin a cat.

[Nickfromwales]

Poor cats  

[Declan52]

No need for a parge coat as this build is in NI so with block and block it will have a scratch coat and then skim on the inside and scratch coat and whatever finish is going on the outside, k-rend dash etc.

How they build it will depend on the height, bungalow or 2 storey. Most self builds here use trestle and plank to get to wall plate height, first floor joist height and build overhand which means they build the outside skin first then the inside skin, insulating as they go. What size is your cavity and what are you doing for insulation??

[Dave Jones]

8 hours ago, nod said:

Sorry Nick 

Your wrong 

Dot and dab can be made extremely airtight I’ve been doing this for forty plus years 

We use hundreds of bags of Parge each year Even the housing associations have stopped using it for airtightness Always for sound 

The only time I use it is on some self builds and I always tell my guys that it’s not for airtightness 

Making sure that the block work is pointed and bar jointed and around joists also 

15 plus years ago you could see into the cavity as the Brickies new we would come along and seal everything 

But that stopped overnight 

 

 

interesting.

 

from my understanding, brushing a sloppy sand/cement mix over them prior to dabbing ensures any tiny shrinkage cracks are sealed. 

 

Agree they should be gagged properly anyway but it doesn't take long to brush a slurry over them for belt and braces.

[SteamyTea]

10 hours ago, Nickfromwales said:

Airtightness is inside, and not outside.

Not sure I agree there.

You can make a room very airtight on the inside, but if you allow air to pass though the insulation layer, then the performance is reduced.

Each element has to be dealt with in both isolation and as part of the whole.

 

[Nickfromwales]

3 hours ago, SteamyTea said:

Not sure I agree there.

You can make a room very airtight on the inside, but if you allow air to pass though the insulation layer, then the performance is reduced.

Each element has to be dealt with in both isolation and as part of the whole.

 

You make the room airtight on the inside SO it doesn't GET to the insulation layer. Funny why all AT layers I've ever seen are at the immediate room interior? You cannot allow air to migrate into the structure, as managing its arrest after that is like herding cats ( aka impossible ).  

[SteamyTea]

38 minutes ago, Nickfromwales said:

You make the room airtight on the inside SO it doesn't GET to the insulation layer. Funny why all AT layers I've ever seen are at the immediate room interior? You cannot allow air to migrate into the structure, as managing its arrest after that is like herding cats ( aka impossible ).  

As I said, it cannot be looked at in isolation.

The airtightness on the inside is really about moisture migration mitigation.

Then, in the UK, the 'layers' get less vapour tight, not vapour tight, no mention of airtight.

This leads to a problem that people think that the VCL is all that is needed, if this was the case, then just hanging any old type of insulation on an exterior wall would solve high energy usage.

So it must be pointed out that, as I mentioned here:

3 hours ago, SteamyTea said:

Each element has to be dealt with in both isolation and as part of the whole.

Saying otherwise is giving bad advice.