new houses with chimney stacks now sporting a black external metal flue....

The chimney stacks may be nothing more than a decorative feature but in any case the flue required for a multifuel burner will have to meet insulation and anticorrosion standards

Also, modern houses are built to a certain level of airtightness. Putting a socking great chimney in a house blows a hole in your airtightness score. That's why they're using balanced flue gas appliances, duct non return valves and so on. Basically so the expensively conditioned (heated) air stays in the house and doesn't leak out (MVHR can be used to keep it fresh, trickle vents are a cheap and poor substitute). The chimney the housebuilder put on is either purely decorative or carriers their boiler flues or soil vent.

The homeowner, who doesn't know about airtightness, then drills a huge hole in their thermal envelope to install a flue for a woodburner. They torpedo their airtightness, resulting in a house with more draughts and more leakage of their heated air. But nobody tells them about this.

Theo

SH snipped-for-privacy@spam.com wrote

Weird.

Maybe they were required to have fake chimney stacks as part of some insane scheme to keep new houses looking like the existing older houses. There have been some stupiditys like that on Grand Designs.

So they are only fake chimney stacks.

Heat? I've never considered it a good idea to still put chimneys into new houses. What is the point. I suppose boilers might need them, but if we really are serious about heat pumps, why bother, you don't need much more than a vent to get rid of cooking smells or even steam, but in the latter case you might prefer to use the heat and recycle the water. Brian

Because they’re probably fake chimneys. To people of a certain generation, a house without chimneys just doesn’t look right.

Tim

Watching new houses being built, we noted that the bigger ones had chimney stacks. Then looked at the building materials and they were one piece dummy chimneys, purely for looks. I assume that in the new builds this is a standard cosmetic feature. To support a real chimney stack you would have to have all the brick/block work from ground level based on a strong hearth, which costs money and also reduces the internal space.

A real chimney - why? If you need an appliance then you would install a flue.

Cheers

Dave R

See almost any child's drawing of a house. Lollypop tree in the front garden, of course.

The new build my daughter lives in is simply a decorative feature. Watching the build of the other houses on her development, the “chimneys” arrived fully assembled to match the brickwork and were craned up onto the roof and perched on the inner cavity wall and the first truss then the outer brickwork was built up to the chimney

Richard

That is silly. Maybe they put them on for somewhere to put dishes and tv aerials?

The houses behind me were built in the late 60s and early 70s and none have chimneys, They do sometimes have a kind of flat cover thing with a gap all around that steam can come out of. Brian