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Wednesday, 20 November 2013

Which qualifications does your builder have?

Most of us will have no idea what qualifications builders have. We invite people, for a number of different reasons, into our homes to work on our most expensive assets and yet, we don't know whether they are qualified to do so.

Is this madness??

I am currently doing some work for the Construction Industry Training Board on training for construction professionals at NVQ Level 3. Looking at the qualifications from Level 1 up to 3 it does seem that anyone holding Level 2 should be able to do most things on more recent housing stock. So why do we see so many mistakes with common building work?

Last year I was speaking to Cardiff and Vale College and it seems as though a common occurrence is that people start their Level 1 (this represents a basic understanding of the topic and the main basic key skills), but only a relatively small percentage come back to do their Level 2 (this represents the industry standard - what people need to know to be able to do their jobs properly). Where do they all go? Well it seems that some decide that it is not for them, but many others start work.

So in this country we have the ridiculous situation where anyone can put a Builder logo on the side of a van and start trading as a legitimate business. No need for a qualification, no need to show that you understand how buildings work or that you can undertake the more complicated work with confidence, competence and skill.

In other countries you have to have a qualification to build, but not here. So bear this in mind when looking for a builder. Also the marks associated with FMB and NFB are worth noting. They do require a portfolio of work to be seen in order to join, but no official qualifications. So there is some reassurance here, but again no training.

Whilst there are some issues with the standard training, especially since we don't recognise the differences between modern building materials and practices compared to the historical ones required for lots of refurbishment work, it is the best way of at least having an underlying competence. So look for a minimum of NVQ Level 2 for standard works, a Level 3 for more complex requirements and a Level 3 Heritage Skills qualification for work on pre-1919 buildings. If there are no qualifications to be had, then look for a portfolio of work and references.

Good luck!

Tuesday, 19 November 2013

Green Deal Measures - What are they installing?

On the news that the Green Deal has installed 1,000 measures I thought that I would have a look at what they are actually doing.

I was pleased to see that the bulk of what is being done is really quite standard and unlikely to cause damage to the housing stock. Most of the work is changing people's boilers to more efficient ones (37%) and also the related improved heating controls (15%) and hot water tank insulation (9%). Then there is the standard stuff like loft and cavity wall insulation (10%). The only real surprise was that people are having photo-voltaic systems installed as well (16%). The high interest rate associated with the green deal would counteract the financial benefit accrued by the Feed in Tariff, so one must assume that people are doing it for all the right reasons (ie to cut carbon emissions and to localise energy production).

Not too many people are doing solid wall insulation (14%), so this is reassuring, especially since most of the activity in this area is being completed on more recent solid walls rather than the pre-1919 types. Working on concrete walls is much less risky than brick and stone walls.

So even though I am not a fan of the Green Deal, due to all the issues of the poor advice generated by the software, the cost of the loans and the inaccurate financial projections given, it does have a use. Where people cannot afford the capital for 'improvements' this is a way of giving people access to the money to make some positive changes. So even if the measures prove not to be cost effective for the recipients (although with the price rises recently announced even the poor calculations given might find a 'Get Out of Jail Free' card) at least there are some apparent carbon reductions for the rest of us.

Thursday, 7 November 2013

Lime - that's less than half the problem!

Sustainable and historical bodies talk about the need for lime renders and mortars in pre-1919 solid walled buildings and rightly so. Lime is a porous material and will allow moisture to pass through it. This allows the walls to 'breathe' and so can help to keep them dry.

All well and good. However, when you make up a mix of lime render what is the main constituent? Lime? No, the bulk of the material is the aggregate. I think that this can be a problem, because the main aggregate that we use is the cheapest and most common one. Sand.

Sand is not breathable / porous and so if you use lime and sand for renders then all the moisture can only travel through the lime. Given that rainwater is slightly acidic means that the lime will be weakened more quickly. However, if porous aggregates are used (or at least a portion of the mix is made from porous materials like limestone, brick dust etc) then the aggregates will take a lot of this load off of the lime, thus making it last longer. Also if external finishes are meant to be 4 times more breathable than the main structure then having a porous aggregate helps to achieve this. 

Lime with a porous aggregate is also more likely to work in an 'osmotic' manner rather than in a capillary way with sands. This means that it can 'suck' moisture out of walls more easily. So as you can see the term 'Lime render / plaster' needs a little more clarification.

I think that the choice of lime and its associated aggregates needs to be more scientific in its specification, especially since choice might also be driven by a range of other factors including:

Underpinning substrate 
Historical colours of renders

So we need to be careful. The best for renders are a mix of particle sizes and sharp angular edges and so if we allow ourselves to be driven by factors like historical use we need to take care. Many old render mixes were dictated by available local materials and these might not be best suited to the location etc, so planners might insist on a mix that is not particularly appropriate for the building!

There are other issues that surround all of this including:

Sand types (smooth or angular)
Salt contamination
Application methods

However for the sake of brevity, are there any broad recommendations that I can give?  

Well, after much thought I have ended up in the Welsh Lime Works camp where we tend to advise people to use lime putty (based on limestone rather than chalk) with a limestone aggregate, applied with a pump and then finished off with a limewash (again based on limestone). This creates a very breathable mix that allows buildings to work in harmony with nature, but it is worth noting that all projects needs to be individually approached.