ᐅ Single-Family Home Masonry – Choosing the Right Poroton Blocks for Us?

Good day,

we are planning to build a single-family house and have received initial offers. I am currently trying to decide on the best choice for the exterior walls and would like to ask for your advice.

Our priorities are:
1. Walls as slim as possible, since the single-family house will be narrow and long due to the shape of the plot.
2. Good thermal conductivity
3. Effective sound insulation

We have currently been offered:
Masonry for the exterior walls on the ground floor and attic made of Poroton bricks (Wienerberger, Röben, or equivalent) 24cm (9½ inches) thick. Clear structural height for ground and upper floors 2.62m (8 ft 7 in). Interior masonry 17.5/11.5 cm (7/4½ inches) thick made from hollow bricks, to be constructed according to structural requirements. Knee wall masonry height 1.36m (4 ft 5½ in).

The exterior walls will be finished with thermal insulation plaster consisting of rigid foam panels 20cm (8 inches) thick with fleece reinforcement embedded in thin-layer mortar and a mineral textured plaster (white).

My thoughts so far:
From what I have read online, almost only T9P, T8P, or T7P systems are recommended nowadays, often with versions including mineral wool insulation. Sometimes the T14 system is still mentioned, usually without perlite or mineral wool. I find little information about the T18. Is the T18 outdated and therefore something I should rule out?

According to my research, I would actually prefer the V-Plus system from Schlagmann, or as a substitute for the T18, then the T14, or if budget allows, the T9. Or should I, due to the thinner exterior wall, rather choose a T7-P/MW or T8-P/MW?

At the moment, I’m still uncertain, but I tend to follow my gut feeling and lean towards the Schlagmann T14 with the V-Plus system and for the interior wall, the planer brick T-1.0 or T-1.2.

Finally, I have a question regarding the hollow bricks used for the interior walls: what should be taken into consideration here?

Looking forward to your tips and suggestions.

Best regards

Hello,

You have a 20cm (8 inches) thick ETICS (external thermal insulation composite system) on your wall, which is responsible for the insulation. The insulating value of the brick itself then becomes almost irrelevant. Therefore, I would recommend using a dense and heavy brick for the exterior walls, either a T18 or possibly even the perforated bricks normally used for interior walls. More mass in the wall improves soundproofing.

Ask your shell builder if they really want to use Wienerberger. In our case, Wienerberger T18 plan bricks were offered, but our builder asked me for approval to switch to another supplier. According to him, Wienerberger is currently experiencing serious quality issues. The bricks are very warped and uneven.

The V-Plus system is said to be quite good (according to my builder and my expert, it’s almost essential with plan bricks to ensure that every brick layer is fully covered in mortar), but it is quite complex to work with and will increase costs accordingly.

First, you need to decide whether you want to build monolithically (T8) or with ETICS (T18 plus 15-20cm (6-8 inches) insulation). If you go with ETICS, the brick doesn’t need to provide insulation.

Pick up a T8 brick and take a look. The stuff is as delicate as fine china. You can’t just screw or fix things into it, and it doesn’t offer great sound insulation either.

Best regards,

Andreas

Thank you for your reply, Andreas. So the T18 is not an old or inferior brick and could definitely be kept by us.

Regarding the wall, the architect also told us that he would design it so that all cables, pipes, etc., are concealed within the wall. A thinner wall would be possible but would mean that pipes and cables—for example in the bathrooms—would need to be boxed in. In his opinion, and in mine, this should no longer be the case in a new build.

What I cannot understand are the perforated bricks for the interior walls. Can someone tell me more about these or what should be specifically considered? For example, the raw density class concerning sound insulation?

Whether we should use an external thermal insulation composite system (ETICS) / external wall insulation (EWI) is a good question. I basically have no objection. What was offered sounds reliable. Or is there any reason not to use ETICS/EWI?

Since the T14 is similar in size to the T18, should we prefer it? Then from Schlagmann?

Many thanks

Without external thermal insulation composite systems (ETICS), your wall construction would be thinner. Your shell height of 2.62 m (8 ft 7 in) seems too low to me; have you checked it? The finished ceiling height might end up around 2.45 m (8 ft).

Regards
Sabine

ETICS (external thermal insulation composite systems) always adds an extra step. I would still prefer to build thick walls. Even with ETICS, the walls are thick, and you avoid ugly gaps in front of the windows.

If you want high sound insulation—and need it, of course—calcium silicate blocks are also a good solution. Then use cavity insulation combined with facing brick or external thermal insulation composite system (ETICS).
A rough ceiling height of 2.65 meters (8 ft 8 in) is too low (without knowing your floor structure in detail).