Wind Tightness

Wolfhound14

I am currently gathering quotes from Timber Frame Companies and one of the companies has a quoted extra for Wind Tightness.
i.e. Supply and Fit of Wind-tightness tapes to external envelope.
Cost is about 2% of the quote for the frame

Does anybody have information on what wind tightness does? Is it basically taping the external joints and more importantly, what difference will it make to the build?

Spillane

Wind tightness is an important element in maintaining the efficiency of passive or low energy wall and roof elements. It helps with the efficiency of the insulation, once the house has been heated, the heat remains in the walls and roof, if wind is coming at the walls and roof, it reduces the effectiveness of the insulation. If the wind is not able to get at the insulated walls and roof, and they have proper ventilation on the external side of the wind tight membrane, then the wind passes through the ventilated area while not disturbing the insulated walls and roof, and allowing the breathable wall to still breath, and the wall to remain hot.

A bit of a mouth full, but I hope this helps.

Alan

gman2k

Ahem,
FYI It's airtightness,
Now, air leakage is the exfiltration or infiltration of air through unintentional paths in the building envelope caused by imperfections in the dwelling construction.
By limiting the leakage of heated air from the building to the outside it is possible to reduce energy consumption as heated air leaking from the building requires additional energy to maintain temperatures.
All new dwellings now have to achieve a certain level of airtightness, and will also need to be air permeability pressure tested using a blower door fan.
This is not optional - it is the law of the land.

It is now generally accepted that mechanical heat recovery ventilation is the best way to maintain a comfortable level of ventilation in dwellings that achieve the necessary airtightness level.

For what it's worth, what your Timber frame companies are telling you should be taken with a large grain of salt, as what they are proposing is merely a step on the process towards overall airtightness.
To repeat and clarify, you will need to do a lot more to achieve an adequate level of airtightness in your proposed build than just doing what the timber frame erection company are saying.
Airtightness needs to be looked at holistically from a design point of view, and careful detailing and then attention to detailing on site during construction stage is required.
If you have a designer involved in your build, ask them what details have they incorporated into the design and detailing to achieve adequate and required airtightness.
If this person does not give you the right answer, and this person is also the one signing your certification for the build, then you need to get the advice of more experienced and qualified construction professionals before you go further.
This also applies to all aspects of the Building Regulations.
I presume your designer has carried out DEAP assessment on the design, and there is an element of renewables involved? I.E. solar, heat pumps, pellet burner etc?

Spillane

Ahem,
I'm sorry gman2k, but air tightness is a completely separate thing to wind tightness.

What you said about air tightness is correct, no arguing there, and is equally as important. But the two are not connected. The inner leaf of the timber frame structure is where the air tightness taping and membranes are, and the external side of the timber frame structure is where the membranes and taping are for the wind tightness, and if you refer to my previous post, the reasons and needs for wind tightness has been explained.

Alan