In this episode specifically, I am going to be talking about the various different manufacturers of wood fibre insulation, the differences in their products and the similarities in their products and also all the things that you need to consider when you’re buying your wood fibre insulation.

So firstly, there are various different manufacturers.  If you Google around, you’ll probably come across four or five.  The main ones that you’d come across would be Unger Diffutherm, Pavatex, Styco, Gutex and there’s a company called Schneider as well, who sell through in Ireland.  Each different company tends to sell through a different distributor in the UK and obviously each different distributor is going to want to say, “Well, our system is better than the others because of X,Y and Z.”  But in the last 10, 12 years of being in this industry, you do get a feel for the differences between the systems and generally they all sell good quality products.  They all have to meet a minimum manufacturing standard, so obviously that’s there to ensure that the products are a good quality, and they all have different boards as well.  So different manufacturers concentrate on a different type of board for different purposes.  Generally you’ll find that each different manufacturer is probably suited to a different type of project or slightly different type of project, which may or may not be more applicable to what you’re doing.

Whilst each different manufacturer has a different product range slightly, they all are essentially very similar in a lot of ways – but the biggest difference that I’ve come across really is actually the way in which the board is manufactured and less so, by who.  As I’ve said previously, there are two different ways of manufacturing wood fibre boards. 

Now the first process is wet processing and essentially you take chipped timber – so all waste timber – you grind it up and then you boil it up with water and a few other chemicals designed to break down the timber into the fibres. You strain that and you’re left with the wood fibres themselves and then you pour that onto what is essentially a sieve.  You compress it down to a 20ml layer and then you steam it.  That 20ml layer is held together purely by the lignin around the wood fibres, so that’s the lignin from the tree. That holds the whole board together and then to make thicker boards you simply laminate up the 20ml boards into thicker boards.

Now, wet processing creates a product where the fibres are essentially in a very similar situation to how they are in the tree.  They’re quite well connected to the neighbours and so that means that one fibre can transport liquid water from itself to its neighbour and so on down the chain, and actually enables it to transport liquid moisture very, very quickly.  Now that has really useful applications in certain scenarios and equally that can be a problem in others.  So, it’s just to be aware that that’s how wet process wood fibre works.

Now the other alternative essentially is dry processed wood fibre boards.  These are made in the same way, so the initial process is to take your chipped timber.  This is then dried and ground up, refined, and then it’s sprayed with a PMDI glue.  That’s essentially a polyurethane glue, but so as to not completely waste my chemistry degree, PMDI stands for polymeric methylene diphenyl disocyanate.  As I say, that’s essentially a type of polyurethane, but it’s used in a lot of products.  It’s used in MDF. It’s used in OSB. It’s a very widely used glue.

Now commercially obviously you want to use as little as possible to create your product because it costs money, but the biggest difference between them is that each individual wood fibre tends to be wrapped around with a coating of this glue and so it’s very, very, very much less able to transport liquid moisture.  One fibre can’t transport it to its neighbour because it’s got this barrier of glue in the way.  That has really useful applications actually. A board that doesn’t soak up water is very useful in certain scenarios, but equally there are other scenarios where the transport of liquid moisture is actually a really important property of the board.  So it’s just to be aware that wet process and dry process boards are not interchangeable in all scenarios.  In some scenarios they are absolutely, but certainly not in all. Important to know that.

Unger generally concentrate on wet processed boards.  Pavatex used to concentrate primarily on wet process but now have a big mix of the two.  All of their internal wall insulation systems tend to be wet processed, but everything else pretty much is dry processed.  Styco, again, similar mix. Gutex and Schneider tend to be predominantly dry processed.  So be aware that when you’re buying from those companies, you do need to look at how it’s manufactured.

You’ll tend to find that dry processed boards are much cheaper than wet processed and that’s simply because of the amount of processing involved means that the product just doesn’t cost as much.  This is what’s driving certainly some of the commercial decisions about which boards to supply and obviously develop the market with those boards.

So once you’ve decided which type of board to choose, it’s important to go through the manufacturers and actually look at their technical detailing and their recommendations for installation and really to see how detailed that is.  Some manufacturers are quite vague about how you install their products and there’s not a lot of detailed support.  Some others are actually very good at helping you install the board. They give you a lot of information about how to install the product, where to install it, where not to install it and there’s a lot of detailed support.  This essentially demonstrates that the manufacturer has a really good grasp on how their product should be used and how they can help you to install it.  So that’s a useful thing to look at.

Unger are pretty good at that.  Pavatex are pretty good at that. Styco are reasonable. Gutex and Schneider, I’ve been less able to find about theirs, to be honest.  Not that there’s anything wrong with the product, but I’ve certainly not found the detailed understanding that you would generally come across from maybe the other three.  So again, once you’ve decided on the manufacturer, the other things to consider really are the components.  So again, most of them do tapes and membranes, certainly Schneider, through Partel do a big range of membranes and tapes.  They’ve got obviously a good support with all the components.  Again, Gutex as well with Ecological have a huge range of air tightness products, so really good support on that side – and the other three do as well, Unger, Pavatex and Styco, generally all sell the air tightness side.

The final thing really is if you’re looking at renders, different manufacturers use different render systems. Some are their own specific render, some use a third party’s render that has been tested onto wood fibre.  It depends whose system you’re going for as to which render you’ll end up looking at.  Often really useful to get a good understanding about render, what it looks like, how it’s put on, how it compares to the way that other people use their renders.  Now, generally most render systems that go onto wood fibre are pretty thin, so you’d use a thin layer render, typically 5 to 6ml along the basecoat and then between about 1 and 3ml on the finish coat.  There are some systems that have got anything up to 20, 25ml on the render systems, which rings alarm bells for me – mainly because it’s the only one on the market. I would tend to stick with the thinner render systems, also partly because wood fibre tends not to carry a huge amount of weight like that.

Anyway, so hopefully that gives you some idea of the things to look at when you’re choosing your manufacturers and if you have any further questions about sustainable building materials, please feel free to email me at Chris@backtoearth or alternatively give me a ring on 01392 861763.

Thanks for listening.