Jes, professional plastering and rendering
We have used Bauwer rendering materials externally on our 300-year-old stone plinthed cob house, in place of traditional Lime render (and of course the no-no material often used by unscrupulous, ignorant builders - cement!). The construction leads to three principal issues:
(a) lack of thermal insulation due to the high conductive capability of the stone, this being exacerbated by thermal bridging across tie stones and earth bridges,
(b) rising damp, and
(c) vapour permeation from the building interior condensing at the dew-point within the wall.
We wanted the walls to continue ‘breathing’, and the Bauwer ‘Light’ looks, in specification terms a very useful material: moderately good insulative properties but most importantly respectable water vapour permeability: ‘breathable’. We’ve put around 50mm total render over the entire exterior stone plinth wall, in around 5 layers: two initial layers of ‘Standard’ around 12 mm thick, two layers of ‘Light’, also 12 mm thick, and two skims of ‘Finish’ with 4mm glassfibre 160g mesh. Layers of Standard & Light were approx. 10mm each, mainly ‘cause the builders (plastering experts of 50 years practice) hadn’t used the Bauwer materials before and wanted to play things safe thickness-wise; as things went on the guys quickly switched from circumspect to very ‘pro’, very much liking the easy knock-up, low density and application.
The Bauwer Finish, like Standard and Light, 'firm-up' very quickly after application and don't like to be trowelled much. We were able to achieve a reasonably smooth and flat finish (much better than Lime-Putty based render, for sure). We haven't painted Finish yet - we'll use Seciltek silicate paint- but I notice that wet std/light/finish dries-out really well, indicating very good moisture transmission and breathability. My recommendation re Finish is that you need to be fast and not trowel much.
We have now to finish-paint, which will be the Seciltek silicate stuff with Secitlitek primer under, as will the remainder of the cob walls, which were last limewashed around 8 years ago. So now we’ll find out, over the coming winter, how much difference is actually achieved in thermal and wall dampness properties: I’m expecting the outcome to be good, as external insulation is a far superior solution (to the thermal problem of old housing stock) than internal insulation. For any building needing water vapour breathability - i.e. most over 60 years old), these lightweight permeable renders are an ideal solution.
Jack, DIY user
Though it might be helpful to note first impressions of my own experience using Bauwer Light. My project is a 100 year old stone cottage in Western Isles that we have stripped back, removing all existing timber frame and lath & plaster - all in very poor condition.
After lime pointing and repairing internal walls my nest step was consideration of effective insulation, especially of materials sympathetic to an old house. I am no expert but my research has convinced me that air vapor permeability is an advantage, meaning many of the current phenolic-based systems were ruled out.
That left woodfibre batts within a frame - until I discovered Bauwer!
For my own project it seemed well suited - it made sense to have just one physical barrier ie a well-insulated wall as opposed to a cold wall, air space, woodfibre insulation, boarding then plaster. It seems over complicated for what is in the end a fairly simple task - keeping a old house warm.
Following instructions and the online video it matter of few minutes to mix. Application was easy with high adhesion to the wetted stone surface. The resultant mix was very easy to work with This the dried fully after a few days to leave a pleasantly firm textured creamy-coloured - and insulated - wall.
Seemed to do exactly what was required in a simple, straightforward and cost-effective material.
A successful experience and so far so good.
Steven, professional plastering and rendering.
Both the standard and the light were easy to mix and apply. They are very light to use and can be used to build out thick areas. I was most interested in the drying times and I am pleased to say that the standard seemed to hardened up quick enough to be able to spray top coat plasterers within a few days. The only issue I can for see is that it’s still not really hard at this stage so other trades could damage it easily. I’m guessing it’s just a case of making everyone aware of this.
Gareth, professional plastering and rendering
All round good experience. Having used both the Bauwer light and standard, I can make the following comments. Easy to apply ,rules off like a conventional render and trowels up like skim. If you consider the thermal properties that Bauwer offers then I would always use Bauwer above hardwall or one coat plaster.
I look forward to using Bauwer again. Thank you to Alexander for good advice and assistance.
Chris, professional plastering and rendering
I used the Bauwer light and thought it was great used it for some dubbing out that was about 50mm thick. Mixed it up and slapped it in with some mesh and the stuff didn't even move its great lol. I can see me placing a few orders with this when the need comes up.i messed about with it for a bit and it floated up nice too.
Andrew, DIY user
I measured 12L into a trug, I was tempted to add a little more water but was glad that I didn't as after mixing the consistency was good. As a complete plastering novice I was really pleased with how easy it was to apply even onto my curved window reveals. Some areas need some more work before a final finish but that is mainly down to not being able to use a straight edge on some areas. I would definitely use Bauwer products in preference to the cork and lime product that I had intended to buy from Mike Wye.
I have just tried putting the palm of my hand on the surface of a rendered south facing window reveal that I lime and sand rendered before I had heard of Bauwer products, it feels cold and damp. Whilst the Bauwer covered reveal, to the same window, feels warm after a couple of seconds. The thicknesses applied were pretty much the same in both cases. So it looks like I will be hacking off the render, shame I got a fairly good finish to it!
Gary, professional EWI and IWI installer
We applied 50mm of Bauwer Light to the block wall, building it up in passes to establish if the product would roll under the trowel. The product showed no signs of any rolling and we could have gone on a lot thicker. Very easy to use and finished well enough that just a paint coating could be applied. The internal product, Bauwer Standard, was equally as good in our opinion as Bauwer Light.
Garyth, professional plastering and rendering
Tried Bauwer Light and we are very impressed. Very easy to apply a great smooth finish. Having use the product now I would have definitely use it the next time the situation arises.
I've tried posting a review of your product but haven't been able to find the link on your site. It's a great product and something I will definitely use. All the best. Garyth.