Drilling patterns

-

Best practice drilling patterns

From COSYTHERM WHITE WOOL CAVITY WALL INSULATION Agrément Certificate No 01/3789

7.3 Injection holes are drilled in a diamond pattern at approximately 1.35 m centres. The topmost injection holes should not be more than 350 mm below the upper edge of the cavity and not more than 1.0 m apart. The bottom row of holes should start approximately 800 mm above the dpc level.

From the BBA cosytherm certificate -  recommended drilling pattern.

The bottom holes are 0.9m above the ground level where the damp proof course but in places it's even higher being 0.8m from the bottom of the incomplete render (which is not the damp proof course).


The horizontal interval between holes is consistently around 1.16m rather than 1.35m as specified

The vertical distance between holes is 0.64m rather than  1.35m


Summary

Although there will inevitably some variation in drilling patterns to match brick/mortar boundries and to work around features such as chimneys. This installation falls short of the BAA certificate recommendation.

Comments

Post a Comment

Popular posts from this blog

The controversy over Cavity Wall Insulation 'topups'

-
Image
In this article I talk about the practice and problems of topping up insulation when voids are discovered, why it is being done and the potential violations of building regulations. I can only put forwards what I have understood from public documents and personal correspondence  So I welcome corrections or clarifications from the industry on this important issue for home owners and will happily update this post to reflect any inaccurate statements. We know that 100s of topups are done every year.   From what I can gather : If the BBA have not approved these topups then the relevant local authority building control should have been notified prior to topping up as an 'off licence' use of the product.  It is not clear that the correct procedures are being followed in all cases. Background :Voids are common A void is simply an area cavity between the walls which is missing insulation.  If a void is large enough then the insulation will not be compliant with the meter square
Read more

CWI, Impermeable masonry paint, hard cement and breathability

-
Image
Waterproof or let's call it plastic masonry paint made with silicone or acrylic sounds like a fantastic idea to keep that pesky rain away from the wall. Unfortunately it can easily cause the opposite in terms of moisture management and inflict devastating damage to old solid walls which were originally made with a breathable building envelope. This article serves as a discussion to highlight some of the unexpected problems which show up in the real world verses the limited testing of the BBA certificates and I welcome discussion from anyone interested in this subject. For a good 'primer' on the problems associated with plastic paint in solid walls, Peter Ward from Heritage House has a number of videos of detailing the sacrilege caused by often well meaning tradesmen applying these aggressively marketed products. I recommend watching all his videos especially if you are having any sort of damp problems so that you can avoid the multimillion pound interventions sold by 
Read more

Discrepancies between Internal and external DPC (damp proof course)

-
Image
In a cavity wall construction, one would expect that the damp proof membrane to be at the same level on both walls. It turns out this is not always the case and my house is a good example where the internal wall's DPC is more than a brick lower than the external wall DPC. I didn't even think to check this before reading the CIGA Technical note 14 . This clearly states that if the distance between DPC and ground level is within a brick (as was the case with my property at time of install) then 'numerous other factors' must be assessed before declaring the dwelling as being suitable for CWI. CIGA  Technical note 14 . One of the factors is the relative level of the inner and outer leaf DPC. This is exactly what I found in my property. Ive used a floorboard to show the position of the internal floor. The DPC is clearly a brick below the floorboard and less than brick above the block paving. External leaf DPC is 1 brick below the floor level.
Read more