Air Tightness Membrane without MHRV - is it worth it?

Lemlin

As you can see from another thread, I'm planning to get an air tightness membrane fitted and get draught taping completed on my new home. However, I'm wondering is it worth it if I'm not going with MHRV?

I have two arguments in my head:

For: I may be having vents in the building which may negate the air tightness but the draught taping and membrane will ensure that excess draughts and loss of heat isn't there e.g. the less loss of heat, the better. The vents will lose some heat but at least other heat won't be escaping.

Against: why make the house airtight and then have vents, trickel vents in windows etc. There's no point to having the membrane with vents so I might as well just not bother with it.

Anyone with experience care to comment?

sas

The holes\trickle vents are your planned ventilation.

The membranes reduce\prevent unplanned ventilation.

If you use the membranes etc then you have the choice to change your planned ventilation strategy at a future date.

gears

Lemlin wrote: »

As you can see from another thread, I'm planning to get an air tightness membrane fitted and get draught taping completed on my new home. However, I'm wondering is it worth it if I'm not going with MHRV?

I have two arguments in my head:

For: I may be having vents in the building which may negate the air tightness but the draught taping and membrane will ensure that excess draughts and loss of heat isn't there e.g. the less loss of heat, the better. The vents will lose some heat but at least other heat won't be escaping.

Against: why make the house airtight and then have vents, trickel vents in windows etc. There's no point to having the membrane with vents so I might as well just not bother with it.


Anyone with experience care to comment?

If its a budgeting issue, even try to get the ductwork in now and then buy the unit at later stage.

Jimbo

Definatly duct for it if possible.

Air tightness membranes should be installed in all new houses with or without mhrv.

There are also health benefits to mhrv. If you have the budget, go for it.

Lemlin

Can anyone pm me the name of a company who provide both services?
I thought it might be a bit cheaper to get a company to perform both - draught taping/membrane and then MHRV.

RKQ

Air tightness is a requirement of the Building Regulations.
It is a proven technology on the Continent. It will save you money.
Its not about building a submarine - its about controlling draughts & heat loss.

Pipe for MHRV now if funds allow.

YourAverageJoe

i found that the ducting was about 2/3rds of the cost of mhrv so you will probably end up going the whole way if you put in the ducting.

MicktheMan

RKQ wrote: »

Pipe for MHRV now if funds allow.

A note of caution. The proper design and layout of the ducting for mhrv has a huge effect on the success or not of a mhrv system's overall efficiency performance especially if the ducting or any section runs outside the thermal envelope.

Lemlin

We've decided to go with the MHRV. I've already contacted a few suppliers and one, recommended on here, has said that they can install the MHRV with two units for 6k. They are a company in Galway and seem to get good feedback wherever I see them mentioned. If anyone else has companies they'd recommend, please pm me.

Now, just wondering, what allowances should I be making to improve airtightness for the MHRV and draught taping?

The plan is to pump wall insulation into the cavity block. We're putting 50ml on the inside wall. Is that enough?
I've also been told that we need to scratch coat the walls and that the brick work should be very well pointed.