# building dilemma: ventilation of fosse



## SPGW

Each trades(wo)man does his/her bit, they are experts at what they do, that's why I accepted their estimates for work. I am just the client and reluctant coordinator since they don't bother to communicate and have enough choice of work that customer satisfaction doesn't enter their minds. Here's the issue:
New micro-fosse system installed after much debate vs sandbed drainage type, by a firm specialised in that. What happens in the house is not their bag, that's for the plumber. The fosse ventilation pipe, 10cm, has to open at a height above the roof ridge and as distant as possible from roof openings including the chimney, to be acceptable to the SPANC. We already had the debate about a pole vs on/in the house...The plumber has installed the pipe optimally in the house from a technical, but not aesthetic, point of view, leaving a 10cm pvc tube to hide in a coffrage in the bathroom and a corridor, to arrive close to the ridge of the roof and says the roofer needs to attach the pipe to a "tuile douille" at its exit through the roof. But wait, says the roofer, I can't break the roof ridge, and its close to a velux and the chimney and the zinguerie around them. He doesn't want to pierce the humidity membrane and insulation already installed....
Apparently it is not acceptable to SPANC to use the chimney conduit for the fosse ventilation pipe, which doesn't make sense to me, since the purpose is to evacuate the gasses, emmisions contained within, whether from a fosse or a fireplace/woodburner, and conveniently, the chimney exits above the roof ridge level. 
So, my non-expert compromise is to go through the roof below the ridge, close to chimney and attach a vertical pipe that rises above the ridge, attached for reinforcement against wind etc to the chimney. The roofer should be able to adequately seal the exit around the pipe. Any advice welcome!
Looking around, now that I'm sensitised to the subject, I am yet to spot a house with a 10cm pvc pipe rising above the roof ridge as a tell tale sign that they have a new and conforming fosse installation. Does this mean that the current regulations are no more respected than the previous ones... and the age old debate about properties not conforming will go on for some years?


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## Nomoss

I had a fake chimney built in the centre of the house, matching the others, close to the ridge.
It sits on a small concrete pad with a level top, supported by noggins between two roof beams, and consists of a single ceramic chimney _boisseau,_ with a standard _aspirateur_ and cover, so is not very heavy.
It is sealed to the roof by standard flashing, and neatly hides 100mm plastic pipes from the VMC unit, cooker hood, clothes dryer, and a 40mm breather pipe from the main drain.


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## LFBEUSTON

SPGW said:


> Each trades(wo)man does his/her bit, they are experts at what they do, that's why I accepted their estimates for work. I am just the client and reluctant coordinator since they don't bother to communicate and have enough choice of work that customer satisfaction doesn't enter their minds. Here's the issue:
> New micro-fosse system installed after much debate vs sandbed drainage type, by a firm specialised in that. What happens in the house is not their bag, that's for the plumber. The fosse ventilation pipe, 10cm, has to open at a height above the roof ridge and as distant as possible from roof openings including the chimney, to be acceptable to the SPANC. We already had the debate about a pole vs on/in the house...The plumber has installed the pipe optimally in the house from a technical, but not aesthetic, point of view, leaving a 10cm pvc tube to hide in a coffrage in the bathroom and a corridor, to arrive close to the ridge of the roof and says the roofer needs to attach the pipe to a "tuile douille" at its exit through the roof. But wait, says the roofer, I can't break the roof ridge, and its close to a velux and the chimney and the zinguerie around them. He doesn't want to pierce the humidity membrane and insulation already installed....
> Apparently it is not acceptable to SPANC to use the chimney conduit for the fosse ventilation pipe, which doesn't make sense to me, since the purpose is to evacuate the gasses, emmisions contained within, whether from a fosse or a fireplace/woodburner, and conveniently, the chimney exits above the roof ridge level.
> So, my non-expert compromise is to go through the roof below the ridge, close to chimney and attach a vertical pipe that rises above the ridge, attached for reinforcement against wind etc to the chimney. The roofer should be able to adequately seal the exit around the pipe. Any advice welcome!
> Looking around, now that I'm sensitised to the subject, I am yet to spot a house with a 10cm pvc pipe rising above the roof ridge as a tell tale sign that they have a new and conforming fosse installation. Does this mean that the current regulations are no more respected than the previous ones... and the age old debate about properties not conforming will go on for some years?


I wonder why, given that the new fosse must be outside the house the ventilation pipe isn't also outside! Why does it need to go up the inside of the house?


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## eairicbloodaxe

When we had our fosse installed in 2018, our vent pipes (there are two) were installed outside. One runs up the wall to roof height, the other by the fosse itself is attached to a tree!

Kind regards

Ian


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## LFBEUSTON

eairicbloodaxe said:


> When we had our fosse installed in 2018, our vent pipes (there are two) were installed outside. One runs up the wall to roof height, the other by the fosse itself is attached to a tree!
> 
> Kind regards
> 
> Ian


Makes more sense! Having it run from outside into the house and up to the roof seems ridiculous!


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## SPGW

eairicbloodaxe said:


> When we had our fosse installed in 2018, our vent pipes (there are two) were installed outside. One runs up the wall to roof height, the other by the fosse itself is attached to a tree!
> 
> Kind regards
> 
> Ian


Thx Ian, unfortunately no conveniently placed tree, and a pipe running up the wall (or a pole, which we considered) would be impossible to make discreet, based on the position of fosse and house. So, I've asked the plumber and roofer to come up with a solution together.


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