Builder wants to cover air brick

dexterwolf

We are having a conservatory built and the builder has said he wants to cover an air brick on the back of the house when they put the base and floor up to the level with concrete.

Is this ok to do or should it be left as the air brick in what will be the conservatory.

The house is 6 years old so it's not old.

Doozergirl

No!

This is why I hate the things so much. It’s substandard work with no one from Building Control to check that it’s been done correctly and yet peoppe think they’re essentially buying a better priced extension.

It’s very basic building knowledge and very easy to extend the air bricks using essentially drainage pipe and a subfloor vent which costs hardly anything. If he doesn’t know that then I question how he knows how to build anything at all. Has he ever even met a Building Control Inspector?

Furts

A very worrying scenario. The presence of an air brick indicates a block and beam floor. This floor is expensive and built because of poor ground conditions, or because specific foundations have been used. It follows that the only floor and foundations suitable for the conservatory are a similar detail.

I have yet to come across any conservatory that has been built to match with a concrete block and beam floor. What has OP discussed and agreed to be built? Does OP have any interest in a job being done properly?

The fact that the builder wants to cover the air brick says they are either clueless, or bodgers, or outright cowboys, or any combination of these. Does OP really want such people working on their home?

Then consider a broader picture. The vast majority of houses with block and beam floor are woefully under ventilated when they are built. They should receive remedial works to add additional ventilators, but the owners never pursue this. However, there are ignorant folks going around saying "lets block up a ventilator". Your builder is in this category.

Time for a reality check OP. Ask yourself some deep and searching questions. It is your money being spent and it is you who will have to live with any fallout from cowboy building.

gt568

Drifting slightly OT here, I have 2 questions if I may....

1. Why do block and beam floors require airbricks? Is it because the beams are suspended above ground level? What would be the impact of them not being there?

2. My house has a slab floor and foundations, why do I have airbricks?

Furts

The air bricks allow the material under the floor to remain dry. Think about stopping damp and mould here. They can also be venting away radon, methane, or any other gases which exist under the home.

Going back to OP you can then see that by blocking the air brick it could be causing a build up of radon, methane or whatever, all of which could have nasty outcomes. Nobody on the forum can answer this precisely, but it is also likely OP has no idea what exists under their home, nor why the air bricks are there. So it is better to be safe than sorry.

Of course, a competent builder, or conservatory company would have discussed all this with OP!

I suspect you have a block and beam floor, because the beams are cast with a screed, or slab, on top. So they will appear solid.

gt568

Furts wrote: »

I suspect you have a block and beam floor, because the beams are cast with a screed, or slab, on top. So they will appear solid.

No, it's definitely slab. I watched the houses go up many years ago before buying it. That's why I am confused as to why there are air bricks.

The slab was poured in the mid-eighties and then construction stopped till the early 90s.

teneighty

The question is "what is the air brick for?"

Could be sub-floor ventilation as suggested or could be an air vent for a fire etc. etc. Until you know its function you cannot know if it can be blocked, relocated or extended under the conservatory.

I suspect it is there for a reason if the house is only 6 years old so just blocking it could be short sighted.

Furts

gt568 wrote: »

No, it's definitely slab. I watched the houses go up many years ago before buying it. That's why I am confused as to why there are air bricks.

The slab was poured in the mid-eighties and then construction stopped till the early 90s.

You could have a radon sump under your floor and this is the extract.

gt568

Furts wrote: »

You could have a radon sump under your floor and this is the extract.

Is there an easy way I could confirm slab or block and beam? You've made me question my own memory now....

Furts

gt568 wrote: »

Is there an easy way I could confirm slab or block and beam? You've made me question my own memory now....

Nothing comes to mind ...cue others here! A pointer would be this. A radon sump is likely to have one air brick, or perhaps one on each elevation of your home. Block and beam will have the air bricks typically only 75mm high set at regular intervals no greater than 1800mm apart. Whilst these should be on all elevations the easy, quick, option is often taken. Then they only appear on the elevation where the beams are bearing.

Kiran

Furts wrote: »

Nothing comes to mind ...cue others here! A pointer would be this. A radon sump is likely to have one air brick, or perhaps one on each elevation of your home. Block and beam will have the air bricks typically only 75mm high set at regular intervals no greater than 1800mm apart. Whilst these should be on all elevations the easy, quick, option is often taken. Then they only appear on the elevation where the beams are bearing.

No non intrusive way to confirm, but as you say, the number of vents it's the most likely tell tale sign.

OP, it is possible to extend the air brick under the conservatory slab and is relatively quick and easy process. I'd be looking down this route regardless of which type of sub floor you have.