air tightness results

homewardbound11

Hi,
I am awaiting my results but from conversation with the frame company the timberframe achieved 1.35 infiltration and 3.5 on heat loss.
I am guessing one is negative pressure and one is positive pressure.
I am also assuming Q50 testing and have a question.

What i the overall air leakage result in terms of m3/hr/m2 at q50. Is there some formula for using both positive and negative pressurization.

BTW, I had in contract a minimum of 3m3/hr/m2 as an acceptable result.
I am expecting a final test that with all internal walls and floors in will be well less than 2.

MicktheMan

homewardbound11 wrote: »

Hi,
I am awaiting my results but from conversation with the frame company the timberframe achieved 1.35 infiltration and 3.5 on heat loss.

From an airtightness perspective your post is confusing. I have never heard of a heat loss figure for air tightness. You have an infiltration figure for -ve internal pressure and exfiltation figure for +ve internal pressure. These measuresents are taken over a range of pressures (up to 100 Pa) and the final q50 is the average of both +ve and -ve results. The +ve & -ve numbers should be pretty close if the test is done properly.

The figures you give above (if there do represent the +ve/-ve pressures) are way out and imo the test is invalid (someting went horribly wrong during the test, the equipment used isn't properly calibrated or the tester doesnt know how to test!).

Note that having an a/t test done early on in the build is recommended to find and fix weaknesses when it is easy to do so, the final test done when the house is completely finished is the important one as the various trades can have a significant impact on air tightness.

homewardbound11

Thanks for the reply,

When i get the results i will pm you.if you don't mind.
Question is the 1.5 and 3.5 figures of positive and negative that far out afterall. I can see where cases of negative would differ from positive but largely i dont have any knolwedge of the values.

MicktheMan

homewardbound11 wrote: »

Thanks for the reply,

Question is the 1.5 and 3.5 figures of positive and negative that far out afterall.

Yes they are. Imo, their difference is so great that the test would be invalid. Typically you might get a difference of say 3 or 4% between the +ve and -ve tests.