Free advices for high building standards



Thanks for visiting our website. We want to give you some free advices to achieve high building standards for your home.


Counter Battens
Counter Battens

Counter Battens


Please consider the use of counter battens. They ensure a proper roof ventilation and prevent structural damages caused by moisture.

By having counter battens installed, you don´t need a ventilation layer between the breathable membrane and your rafter insulation. That means you can use thicker insulation to get better u-values and less cooling of the insulation through air infiltration.

Taping of breather membranes
How to create a wind-tight roof ?

Weather Tight Sealing


Slates and Roof Tiles are never 100% weather proof. Your breathable membrane protects your roof structure against wind and driving rain.

Please seal (mostly by using special tape) all overlappings, penetrations and connections to roof windows. This is the

only way to make your roof structure completely wind tight.

Roof Window Installation
It´s important to have the right reveal structure for roof windows

Roof Windows


To prevent damages on the inside of your roof window, the right construction of the reveal is important.

When you build the reveal the wrong way, parts of your window won´t get heated and well ventilated in the winter and you´ll get soon or later condensation and mould in the corners.



Perfect Installation of DPC for Window Sills
Perfect prepared window sill

DPC on Window Sills


The DPC should be wrapped around the window sill and the window frame goes on top of the DPC. This is the only way to prevent the ingress of dampness through the concrete of the window sill.

Another great example for MJ window installation
Typical window installation

No compromises regarding Window Installation


Your window supplier charges you the full amount for the installation of your windows. Do not accept any messy installation, caused by "speedy installers". Your new window should last for the next 30 years hence it needs to be fitted in a correct way. 

Bear in mind that the window need a proper airtight sealing afterwards. How do you want to achieve this on a window as seen on the photo?

Appropriate brackets instead of basic straps to hold a window
Basic inappropriate strap to the left, functional bracket on the right

Load bearing capacity of fixings


The photo shows two types of window fixings.

The left strap was originally installed by the window supplier at the bottom of a room-height fixed glazing and will not carry the weight of the window. In coordination with the client, the window got additional appropriate brackets to prevent a drop.


Archaic water-tight sealing made in Kerry
How do you want to ensure a water-tight sealing by using lead?

Lead and DPC are poor sealings


A permanent working water tight sealing can´t be made of lead or DPC.

Please have a look here for the right solutions.


Only plastered walls are airtight
Perfect preparation for the installation of insulated plasterboards

External walls need to be plastered internally


The internal plaster creates an airtight layer for masonry. No matter if you want to use insulated plasterboard or just a hard wall finish in your house, you need to plaster all external walls of your house on the inside. The blocks are too porous on their own and missing pieces of mortar joints will cause draughts as well.

Plaster around joists for timber ceilings creates airtightness
Whereever ceiling joists reach into the cavity, they have to sealed

Don´t forget to seal the joist for the timber ceilings


Many existing houses are struggling with draughts, coming straight out of the ceiling. Please ensure a proper

sealing around all joistes and beams which reach into the cavity. Cavity wall insulation does not create airtightness!

How to ensure airtightness above mf ceilings
MF Ceilings need attention regarding airtightness

Suspended Ceilings are in need of plaster as well


It´s the same principle as shown on the timber ceilings above. The small piece of external wall between the

MF suspended ceiling and the concrete slab need to be plastered as well, to prevent air leakages.

Proof of necessity for perimeter air tight sealing
Perimeter Sealing on external walls

The perimeter should get an airtight sealing


When you´re using screed for restoration purposes or underfloor heating, please seal at least the joints to the masonry around the external walls.

The photo beside shows the difference between the sealed external and the plain internal wall. It was taken during an air tight pre-test in a new building.

Airtight sealing for cavity walls
The most forgotten seailing regarding airtightness

Cavity walls require an airtight sealing


Whenever cavity walls get access to the inner area of the house, the cavity need an airtight sealing too. Typical building situations are sun rooms and ground level extensions, having an external gable on the first floor straight above the beginning of the extension. We recommend to close the cavity first by using insulation boards, as used around the doors and windows. Than you should use an airtight tape or membrane to prevent draughts.

All trades at the building site should take care regarding air tightness
Sometimes they don´t know what they do

Other trades can dramatically lower the air tight performance


Please take care that following trades do not destroy the air tight installation. Especially electricians and plumbers are great in doing

unexpected modifications afterwards. Please remind that the easiest way for their purpose could end in the worst solution for

the air tight performance of your building.

Chasings on exterior walls need to be sealed air tight
Air Tight Sealing of chasings

Attention is needed to prevent air infiltration through sockets


It´s a very common problem in cavity wall houses here in Ireland. Even by having the conduit sealed, there is a noticable draught coming through the sockets and switches. The reason is the untreated surface in the chasing, where air infiltrates through the block and streams up or down along the conduit. If you want to create a house with low air changes, you´ll need to seal the chasing before installing the conduits.


HRV Unit installation
Out of sight, out of mind.

The right place to install a HRV Units and components


The most efficient system is pointless in case you install the main unit or the manifolds somewhere in your cold roof area. How do you want to achieve good heat recovery values when these components are not properly separated against cold?

HRV Ducts lowering insulation values
HRV Ducts are not made for insulation purposes.

Think ahead regarding duct installation


Please keep in mind that your ducts shouldn´t weaken your insulation. Also please don´t forget that they need a proper airtight sealing afterwards, whereever they penetrate your vapour control layer.

Especially for retrofit it could make sense to think about a Ductless HRV System.

Prevent to get your HRV ducts contaminated with dust and dirt during the building stage
Supply of germs and bacterias included

Keep your HRV System protected during the construction stage


Your HRV System is designed to supply you with fresh clean air. Please treat the system carefully during the construction stage and block all plenums and accesses to prevent the contamination of the system. There´s plenty of dust and dirt involved whilst your house is been built and you do not want to get contact between these particles and your air supply.

There is a high risk of contamination for every extract duct of mHRV
Is this looking healthy???

Protect your extract ducts


The extract side of your mHRV is running permanently in all of your wet rooms. It´s a fact that not only air will be extracted, because of a significant amount of dirt and dust in the air.

You´ll see the traces of this pollution clearly around your extract vents and inside of the extract ducts in a certain while. The solution to prevent this situation is already available - you just need to get in contact with us.


The 200mm wide cavity is worthless in the top area where the wall plate is.
The 200mm wide cavity is worthless in the top area where the wall plate is.

Prevent uninsulated parts at your building envelope


The plan was, to use beads for pumping the cavity walls and spray foam for the roof area. Unfortunately there is a triangle which will not be covered by the proposed insulation materials. The cavity needs to get blocked on top for fire safety reasons and the spray foam can not applied into the eve area because of lack of access and missing counter battens under the slates. The actual detail will definitely cause a cold spot on the inner leaf which will end in dampness and mould.


The difference between a poor and a good installation of cables
Which installation would you prefer?

Get your cables installed in a neat and clean way.


It could happen some day that you might need to detect a faulty cable.

Especially when the cables have been laid up and down above your metal frame ceiling, you´re increasing the risk of damaging the sheating around the cable.

This happens because there´s a movement all the time in the structure and the cable can rub on the metal.


Locating external units of air-to-water heat pumps


It´s not the best idea to install the external unit of an air-to-water system facing windwards. If you have not other option, consider the installation of a barrier in an appropriate distance, to prevent that the wind affects the performance of your heat pump.

Do not place the unit to close to your house as well, otherwise you´re risking damp walls in the winter.

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