Why Haven't We Warmed to Porotherm in the UK?

I worked in germany 30 years ago, their construction was far more advanced than we are now. We used to build a floor of a block of apartments and the waste wouldnt fill a mortar tub. Here a lift fills a skip with waste. I cant believe that main contractors have never addressed the waste material here. We used a 250mm cube block, kalksandstein, every opening measured multiples of 250mm, width/ height so there was next to no waste material. Architects, manufacturers still design with metric equivalents of imperial dimensions, instead of designing all openings etc to work brick/ block dimensions. Comical

I worked on site around Berlin a few years back and these were all the brickies used, We used 300mm wide blocks, so no cavity and external wall insulation (EWI) on top. Later I specfied them for a self build in Wales and distribution was the biggest problem but we bought a whole lorry load and the suppliers gave my customer some training to set the job up level.....the build flew up. Only downside was fixing downpipes on through the EWI. I love em. Trouble is if you are building an extension and can get the blocks.....what are you going to do in the afternoon? :-)

I didn't even know these bricks are not a thing in the UK. I'm so used to them here in Belgium that I just assumed they're everywhere. I can literally go buy some at my local hardware store. We have some left over lying around in our garden. I've also seen them used as an insect hotel. I find them very effective at blocking any holes in our rabbit runs.

I am building my own house with clay blocks, they're very common around here (Slovakia). I used 44cm thick blocks for outer load bearing walls, 25cm for internal load bearing walls and 14 cm for the interior walls. The thick blocks have about the same thermal properties as Ytong of the same thickness. You can also get them pre-filled with mineral wool or EPS for even better thermals. They're easy to cut with a large circular saw (the thick ones) and with reciprocating saw or angle grinder for the thinner ones. There is some waste as some arrive cracked, others crack while cutting, my estimate is up to 1% based on the extra orders I had to make. I am currently finishing the wiring, no issues with the grooves for the wires - I did all of them with a cheap Parkside wall chaser. Drilling is no issue either, although you have to be more careful and use better quality drill bits. We built the external walls last year and left the exterior untouched for over a year now and absolutely no issues. Even longer periods of rain make the blocks wet only on the outside for a short amount of time, even in winter. However, I strongly recommend covering the top of the unfinished walls while laying them. Once a lot of water gets inside from the top, it takes a long time to dry. Also, I used a bitumen reinforced membrane for the rising damp, we get a lot of it around here. You can use PVC as well. I have a concrete flat roof on them with insulation and an extensive green roof on top of these blocks weighing around 35t in total and no cracks or issues there either. Overall it's been a pleasant system to work with, especially for a self-builder.

Hi all, did a build with these about 10 years ago, yes on a slab, yes on a sand cement first joint. What is available is a u shaped channel that you can lay at each story height and cast a ring beam in which gives you a really good opportunity to correct any issues. Loved the stuff.

I used these on two houses including external walls and one house done with a single block with insulation. Laid the blocks myself. Happy to discuss the experience. Won’t use anything else.

i used these for the renovation of my slovenian house with a ytong inner lining to the blockwork with no cavity. it was easy to do and the thermal efficency is incredible. our house is warm in winter and really cool in summer while facing -15 to +40 degree temperature swings outside. i really dont understand why they are so rare in the UK. love this product, also weinberger roof tiles are amazing quality

I have a large 350m2 house in Eastern Europe built with Porotherm blocks. They are typically externally covered with 10cm of insulation, then rendered. These blocks are also available with insulation built in.

Historically the UK has often been miles behind in adopting modern building materials. ICF, pipe-in-pipe plumbing, etc. Even PIR-type insulation is relatively recent here. Lots of builders put things up in the manner they were taught by builders who were taught in the 1980s and don’t stay on top of what’s possible. I find there’s more expertise on decent DIY forums these days in terms of what’s new versus what your average tradesman carries around in their head. (And yes this is a generalisation, if it doesn’t describe you then that’s great.)

Used them on my house in italy. Used 30cm thick ones, rendered with sand and cement on outside and inside. Render sticks well. I also 10cm thick ones for internal walls and used a gun adhesive for those. Can put up an internal wall very quickly this way. Took me a few attempts to buy the right wall anchors to hang things but I eventually found ones with a picture of the blocks on the packaging and they worked well.

Hi Roger, in Czechia these are generally all they use for internal & external skins! They then have to be rendered or cladded. Rendering or cladding helps attract moisture and prevents moisture from evaporating. Therefore when you travel throughout Czechia, you will see the rising damp at the bottom of the buildings and the render falling off, and same at top of buildings where water is able to get behind the render/cladding. The rendering and brickwork therefore suffer. As soon as you drive into Poland, you start seeing traditional bricks being used again. The biggest problem is that it is now very hard to find a Czech bricklayer that can do face work, which obviously look great when done right. There are almost no brickwork buildings in CZ which is a shame. I'm sure the cost saved with such material is not passed onto the home-buyer but the future repair bills are! Not being able to get good fixes into the wall is a deal breaker for me and many others!

I first saw these in the Frankfurt Home and gardening show 35 years ago and was impressed with the speed of laying.

I would give them a go, not for a client yet but on my own home to test the water

As a beginner, I used Porotherm for the inner and outer skin, with a 150mm fully filled cavity. Worked like a dream, building control were very happy, and a thin render on the outer skin is perfect. Just make sure the right mix is used fot the render - it is different to standard blocks.

A friend in Wales built his house using these, seems very happy with the result some years later. He had a sound raft base with membrane. Looks a good system .

We have used these on a few small projects for over 15 years. Agree with some of the other comments in that they can be a pain to drill into as they are strong but brittle. We've used them for external walls as well with render finish and they are still totally fine 10 years later. Bricklayers hate them which is the main issue. You can't get them specified unless the main contractor fully buys into training up some lads to do it. The whole point is to use semi-skilled labour and actually folks trained from nothing were better at it than the bricklayers. They even have a 365 wide block which you can use without a cavity and with external insulation and render. Used right, these are an excellent product.

I fitted two windows in my Spanish villa, used these block to block up around the windows, they were double thickness and used them installed to the exterior outer skin, and then skimmed over with capa fina and they are perfectly waterproofed. I bedded between courses with mortar and not adhesive and also fine. 👍

I had a house in turkey for 12 years all the building was fine apart from the first meter internally, it was sucking up moisture but I think it was because the builders didn’t give a flying frigment as to how it was built, i put it down lack of dpc because i did dig up part of the lovely looking patio slabs ( o how very nice ) made to look good for the buyer and no DpC. Every body just needs to the job property.

I used those in my renovation, added a new extention and some new internal walls. Everything was done in 1 days work, i used the dryfix its the foam, its crazy strong that bond i was in disbelieve. Also no mortar or adhesive like in the video needed with the foam, really fast.

Our house in France is built with them. They're rendered on the outside with self-coloured crépi - a rough-cast plaster. The walls are around 400mm thick and this provides decent insulation in winter and summer. The upstairs floor is made of beams with these tile bricks slid in between, then 100mm or reinforced concrete it laid on top. This provides excellent soundproofing, so makes a very pleasant dwelling. The building is 30+ years old and there are no cracks inside.