Rear Extension Dilemma

[redsturgeon]

That very large tree to the left looks a little to close for comfort.
Let's hope the roots don't cause to much damage as time goes by.

The foundations should have been designed to cope with the tree roots based more upon the desiccation factors of the soils.

AiY

Yes indeed. We have a very stable substrate here, chalk. If it were clay I would be more worried.

John

[redsturgeon]

In my experience all conservatories with glass or polycarbonate roofs eventually leak a little, and cause higher maintenance bills. Also difficult to access the main house roof above for clearing gutters etc. A flat roof, for all its well known drawbacks, is probably easier to manage.

Thanks. That nails it for the flat room and lantern option which, as John's example shows, also looks great.

I'd like to make the internal ceiling height as height as possible but the main constraint is the bedroom window. Do you or anyone else here know how much to allow for the depth of the roof?

It depends, mine is a SIP build (structural insulated panels) and they are self supporting across the span. The panels are 150mm thick then furring on top to allow a slope for drainage is another 150mm. Then a minimum of 150mm for framing and plasterboard inside, to incorporate steels. So 450mm minimum. A roof using joists may be more.

John

[88V8]

The glass option could be a runner.... if you are fortunate enough to have trees that will provide shading. Or can plant some - hazels left to grow full height do a good job and are quite quick.
Thermal gain can also be minimised with plentiful automatic roof vents, but summer shading is essential.

Roof cleaning can be a bit of a pain, but a long brush on a hose does a decent job.

If you decide on glass, contact the maker of the sealed units for thei glazing spec and ensure it is followed by the builder.
Our expensive conservatory - 30 years ago, house now sold - had its units thrown in as I now realise, and over half of them had blown within 10 years including the huge and heavy units that made up the roof, whereas the units I myself installed in 1982 were still perfect when we left in 2012.

V8

[csearle]

A couple of photos

Looks so different to when I saw it. Good job! C.

[Nimrod103]

The glass option could be a runner.... if you are fortunate enough to have trees that will provide shading. Or can plant some - hazels left to grow full height do a good job and are quite quick.
Thermal gain can also be minimised with plentiful automatic roof vents, but summer shading is essential.

Roof cleaning can be a bit of a pain, but a long brush on a hose does a decent job.

If you decide on glass, contact the maker of the sealed units for their glazing spec and ensure it is followed by the builder.
Our expensive conservatory - 30 years ago, house now sold - had its units thrown in as I now realise, and over half of them had blown within 10 years including the huge and heavy units that made up the roof, whereas the units I myself installed in 1982 were still perfect when we left in 2012.

V8

Yes, why sealed units blow is quite a mystery to me. Our conservatory, now 25 years old, has had several go. I thought it was because the units should be raised slightly on blocks so they don't sit in rainwater at the base. But I'm really not sure. Anyone have any views?

[88V8]

Yes, why sealed units blow is quite a mystery to me. Our conservatory, now 25 years old, has had several go. I thought it was because the units should be raised slightly on blocks so they don't sit in rainwater at the base.

Although they are glued, units need to be insulated from the world.
In wooden windows, bead glazing does not cut it. Lazy botchers method.
In aluminium, I would be very dubious of systems that do not involve a full bed.

As you say, there should be spacers, bottom and sides. Then the units need to be back-bedded with sealant, onto spacers, and fronted with the same approved sealant, approved that is by the makers. The edges need to be surrounded by sealant, back, edge and sides so as to exclude both water and air.

I have installed units in our C17 cottage which are made from hand-drawn glass. Beautifully wobbly when you look through them.
And so they should be beautiful at £125 a pop for small units and up to £220 for large ones. Plus shipping which was £350.
The approved siliconish stuff (Kawo Elastokitt) was £10 a tube plus shipping, here it is https://www.ebay.at/itm/KAWO-Elastokitt ... SwnYdfYio7

There is also a UK option Hodgsons Heritage Putty https://hodgsonsealants.com/product-ran ... age-putty/ but it is horrible to work with.

Depend on it, the average installer will cut corners on the bedding and the bedding material, if allowed, and will be long gone by the time the units blow.

V8

[scotview]

Our conservatory the nicht, NE Scotland, richt cald !
20 years service and only one roof leak. 20 Deg C and toasite the nicht.



Dilemma is
1 leave well alone.
2 Refurbish roof panels etc.
3 Build new orangery thingy.
4 Reinstate the house roof and build a quite separate garden room with wood burner/gas stove. This seems to be the latest preference.

[PrincessB]

I'm a big fan of the pitched roof and Velux.

I'll admit to having scan read the reponses but my take is that conservatory type structures are bit vulnerable to losing heat and overheating.

The extra roof height is a useful thing, not only does it give a feeling of space, it also gives hot summer air somewhere to go.

If you do some calculations, you'll find you can pepper a roof with Velux (type windows) and keep building control happy, you'll also get plenty of light and Velux have a set of heat reflective blinds that fit quite neatly to keep the Summer sun at bay. They also open.

My extension uses five triple glazed 1m square Velux units (with a 2 x 1m skylight) and since I buggered up the heating calculations is quite happy to maintain a livable temperature when it is -4ºC outside with radiators sized to half what they should have been.

We had to do some Pythagoras on the builders to explain that you can get a longer window when it is on a pitched roof than the floorplan shows. They all fitted without issue.

If the pitched roof fouls an existing window, why not replace the window with something wider to allow the pitch or for the sake of being 'cool' raise the pitch to keep the window in the house proper - Windows that used to be external and are now in the structure are fun.

If your external window is a bathroom or similar, Pilkington Satin glass is brilliant it lets most of the light through and blocks anyone seeing your bottom - You can press your bottom to the glass, but the kind of parties you have are none of my business.

B.

[UncleEbenezer]

I'm a big fan of the pitched roof and Velux.

I'll admit to having scan read the reponses but my take is that conservatory type structures are bit vulnerable to losing heat and overheating.

If I were in the enviable position of starting from a clean(ish) slate in putting up a single-storey extension, I'd be a big fan of the roof terrace on top.

The extra roof height is a useful thing, not only does it give a feeling of space, it also gives hot summer air somewhere to go.

Not to mention the warmest-available air in winter? Surely better to open wide when the summer air gets uncomfortably warm (and go somewhere properly cool when the heatwave hits).

If you do some calculations, you'll find you can pepper a roof with Velux (type windows) and keep building control happy, you'll also get plenty of light and Velux have a set of heat reflective blinds that fit quite neatly to keep the Summer sun at bay. They also open.

Now that I can endorse. Since moving to a house with with an attic room having velux windows, I've been pleasantly surprised by the flatpack-level ease of putting up blinds inside (to regulate sunlight) and outside (to reduce summer heat while scarcely affecting the light or even the view). Even the outside awning blind involved nothing more tricky than standing on a table to get myself high enough and wielding a screwdriver at an awkward angle through the window while holding the window in place ...

But the really pleasant surprise was that the velux windows can be opened for ventilation even in the wettest weather. Now that's real design!

[PrincessB]

Hi,

If I were in the enviable position of starting from a clean(ish) slate in putting up a single-storey extension, I'd be a big fan of the roof terrace on top.

I am too, but it depends a lot on where you live.

A Juliet balcony is a great option as you get air and light without the downside of looking into the neighbours bedrooms.

The extra roof height is a useful thing, not only does it give a feeling of space, it also gives hot summer air somewhere to go.

Not to mention the warmest-available air in winter? Surely better to open wide when the summer air gets uncomfortably warm (and go somewhere properly cool when the heatwave hits).

I made a mistake with my extension and went with the current regulations which I agree can lead to a cooler room than would like at time. If we go away for a few days and the house internals drop to 10ºC it takes forever to warm to comfortable temperatures.

A decent build with proper insulation will drop the heat loss through the walls for 0.1 rather than the standard at the time of 0.3 - Bear in mind that super dooper glass is about 1.0. This is where the calculations come in, you need to do a bit of math on heatload, heatgain and the amount of glass you are putting in.

Those walled side and glass roof conservatory extensions look brilliant but trying living with one.

But the really pleasant surprise was that the velux windows can be opened for ventilation even in the wettest weather. Now that's real design!

Velux are a brilliant company.

Anyone planning anything pitched or flat should spend a while browsing their product range.

They do pop out balconies for attic rooms, there are videos and they appeal to my inner Frenchman. Press a couple of buttons and out pops a little balcony with side rails and the window swings up to shield you from the rain as you light your Gauloise and stare moodily into the fog.

B.