Air Tightness Testing & Taping

L

Lemlin

Registered User
Messages
30
Hi folks,

I'm planning to get an air tightness test and taping of potential draught areas done on my home when its watertight. I was just wondering if some people could answer questions from their own experiences:

1) I understand Homebond can provide this service. Does anyone know of any other companies they would recommend?
2) I've heard a price quoted before of 15 per square metre. Is this correct. My house is 293 square metres so it would cost 4395. Is this correct? I thought it sounded a bit high.
3) Anyone have an idea of what the estimated cost would be for a 3000 square foot house or is the above correct?
 
Sounds like an outrageous price - you would buy a lot of insulation for that! [broken link removed] charge €450 plus VAT.
 
Lemlin said:
Hi folks,

I'm planning to get an air tightness test and taping of potential draught areas done on my home when its watertight. I was just wondering if some people could answer questions from their own experiences:

1) I understand Homebond can provide this service. Does anyone know of any other companies they would recommend?
2) I've heard a price quoted before of 15 per square metre. Is this correct. My house is 293 square metres so it would cost 4395. Is this correct? I thought it sounded a bit high.
3) Anyone have an idea of what the estimated cost would be for a 3000 square foot house or is the above correct?
Click to expand...


The house should be sealed from inside and out, particularly if a highly insulated timber frame construction is being used or if cavity insulation is being considered.
SIgnificant reduction in performance from insulation is experienced in windy weather because the construction is not wind-sealed.
This requires specialist methods to prevent insulation lifting off the inner leaf in cavities and penetration of the breather membrane in built up construction sandwiches.

Take some competent professional advice- BEFORE you build.
No point trying to seal a roof after you've weather sealed it - the wind-proof taping of joints has to happen before the battens for the slates are put on.
Admit you have a limited knowledge, some money to spend and people will fall over themselves to advise you.

Don't approach the project as if you have a clue if you have done very little research on the newer building methods.
You could end up spending a fortune yet only achieve half of what;s possible for the money by not building compliantly.

And for the record, your decision not to put in MVHR on grounds of costs - once again you are approaching this in a piecemeal fashion.
You need to look at the overall measures and do a cost benefit analysis to see where the payback occur.
I don't sell or supply any of these systems - so this is totally indpendent advice I'm giving you.

:)

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.
 
Homebond do carry out Blow Door Air Test, as required by the Building Regulations.

Discuss this legal requirement with your Certifier (Architect, Engineer drawing down your Stage Payments). I think you should / should have discussed air tightness with your BER Assessor.

I suggest that you look at Siga, ProClima and MoyIsover web sites.
These 3 companies supply the tapes, sealants and breathable vapour barrier or membrane to the Irish market.
Most offer a free one day installers course.

The Blow door test helps to find the leaks after the building has been sealed, not before! So get the building sealed ( some contractors have blow door equipment to aid installation).

The price to install membranes & tape joints / around window opes can be 15sqm but this is not based on floor area of the building as the membrane is put on walls or roof only - not the floor. So work out the area of walls or roof to be covered by the membrane.

The wall construction type will dictate if membrane is required or not. Again these decisions should be made prior to construction starting on site.
(As would sealing the ends of 1st floor joist at the cavity junction - in a blockwork house.)

All manufacturers tape seems to cost about €1 per metre length.
 
Lemlin said:
Do you have the name of any of the contractors who complete the taping RKQ?
Click to expand...

No, sorry Lemlin.
Most Carpenters pick it up quite quickly.
Roll along the rafters / studs, staple, lap joints, tape joints.
Its quite simple to do - I did it on my own house in 2003.
(At least people know about Air tightness now and its principles - well people are learning.)
I showed our Carpenter & a few labourers, worked fine.
 
If you contact the companies dealing with the materials they will give you details of experienced, trained installers.
 
One quote I got so far for 3840e included:

1. Supply and fit of air tightness membrane to ground floor and first floor ceilings adjacent to roof space
2. Supply and fit of air tightness tapes to all external windows, doors and roof windows.
3 Supply and fit of sealant tapes etc. to all service penetrations to external envelope etc.
4. Air tightness test upon completion of the above.

Is that a fair quote? I'm getting some other ones.
 
That sounds more like it. Although variance can occur at the junction at ceiling level and how this is being treated with intersections with joists.

Are you getting the roof covered with breathable, windtight fabric & taped at the same time?

I am presuming that your walls are being scratch coated and skim coat finished to achieve airtightness or are you having to membrane the walls with a vapour barrier also?

Just be aware of the dangers of penetrations through membranes by services. It is well worth the additional money to blower door test on completion of membranes, get services to sign acceptance of complete airtightness. Do another test when services are complete to verify that there are no punctures. This way you can identify responsibility for leakages as you progress.
 
The walls are going to be slabbed so should I be getting them to tape the walls as well?
 
I got a new quote for 4800 + Vat. Sounds excessive but is this good value?
House size is 3800 square foot.

1. Supply and fit of air tightness membrane to ground floor and first floor ceilings and second floor.
2. Supply and fit of air tightness membrane wrap to hollowcore slab.
3. Supply and fit of air tightness tapes to all external windows, doors and roof windows.
4. Supply and fit sealant tapes etc. to all service penetrations to external envelope etc.
5. Air Tightness test upon completion of the above.
 
IMO square foot area of the house isn't always a useful guide. The cost is dictated by the membrane used - number of rolls required, if its timber frame or blockwork and labour involved. The blow door test is a certain price. The number and size of external opes is also relevent as each tape is roughly €1 per metre length.

The sealing of the first floor joist is a critical detail. In a blockwork house it involves coming on site at joint level, rolling out the membrane on the front & rear elevations, coming back to site after joists & blockwork between joist is installed - to wrap membrane up back of joist & staple to joist so that blockwork can continue. This isn't difficult to do but it is very important.

A dormer can be more difficult than a two storey. Numbers of penetrations - plumbing & electrics - is also a consideration. Will the attic be included?

Try and roughly work out the wall & ceiling / roof areas, how many rolls? External opes, joints in membranes, taping floor / ceiling junctions with walls. Tape in meters length x €1. Add labour - how long will it take two men to unroll, staple & tape above?

Many recommend scud coating blockwork walls prior to installing insulated slab to improve airtightness. Its worth researching this to get it right. Contact the 3 Tape Manufactures for the latest recommendations.

Always get at least 3 quotes for installation & blow door test.
 
The attic is also included alright. My plan for the wall is to pump insulation into the cavity block. The plan is to pump 50ml into the inside wall. Is that enough? I've also been told that I need to ensure the walls are scratchcoated and that the brickwork is very well pointed. Is that correct?

One supplier of MHRV also mentioned adequate floor insulation.
 
Lemlin said:
The attic is also included alright.
Click to expand...
Thought as much :)

Lemlin said:
My plan for the wall is to pump insulation into the cavity block. and that the brickwork is very well pointed.
Click to expand...
Personally I would not pump bead or fibre insulation into a cavity wall with a brick external skin. Brick is made of clay - all clay soaks water. Also a 150mm wide cavity is required for pumped insulation - check your provisional BER cert.

Lemlin said:
The plan is to pump 50ml into the inside wall. Is that enough?
Click to expand...
Not sure what you mean?
Pump 50ml onto wall?
Do you mean stick, bond or mechanically fix insulated plasterboard onto internal leaf of external walls?

Lemlin said:
I've also been told that I need to ensure the walls are scratchcoated and that the brickwork is very well pointed. Is that correct?
Click to expand...
Scratchcoat of plaster on internal leaf of external walls before slabbing, makes the wall air tight.

Lemlin said:
One supplier of MHRV also mentioned adequate floor insulation.
Click to expand...
Ground Floor insulation or 1st floor insulation?
Sealing the junction between walls and timber joists or hollowcore conc slab is very important. A lot of heat can be lost at these junctions.
 
If I'm using a wide slab and not a hollow core slab, does the slab still need to be wrapped with membrane?
 
Concrete is airtight, this is a property of the material.

You would bond your membrane to the concrete using a specific mastic, SIGA's is Primur, I don't know th other products. This creates an airtight seal between the concrete and the wall structure.
 
You must log in or register to reply here.
Back
Top