Extending and insulating an existing Lean to

[Fazq01]

Bit of a complicated one, please bear with me and ask if I don't make my self clear.

I have a single skin lean too on the side of the house, accessed from the kitchen. It has a corrugated ploycarbonate roof held up by wooden beams supported on wooden supports that have been fastened horizantaly to the original exterior wall and the inside of the new single skin wall. The plastic roof is pitched to allow rainwater to drain. It provides plenty of light and makes it a very nice room (in summer). In winter it is bitterly cold and I want to insulate it.

The Lean too is on the side of the house, but only runs half way down the lenght. I want to extend it to the full length and install a bathroom. I have easy access to services, but not to the gas central heating system or mains gas.

Although the house is not overlooked by any other properties, nor is it visible from the road, the roof of the extension will probably be tile or slate, internally I would insulate it but retain the pitch to maximise height.

I would like ideas about keeping this new area warm, gas central heating is out. what is good? Electric underfloor heating? Is it safe to place under a walk in shower?

Should I make the new part of the Lean to single or double skin?

For the existing section, can I use kingspan or something similar? or would it be cheaper to batten and insulate with polystyrene / rock wool?

Idea please.

 

[Deluks]

Your existing structure is little more than a conservatory/covered walkway/dry storage. If you want to insulate and make it usable you are best taking it all down and rebuilding to the same specs as your new proposed section.
To install a bathroom requires building regs, at very least to ensure that the drainage is up to standards, but the windows/insulation/ventilation and heating requirements will all need to be addressed as well.
Bottom line: You can't install a bathroom in what is commonly referred to as a 'lean to'

Best to start on paper, do some drawings/sketches/plans with specs and detailing.
You should check with the council planning department to make sure you can proceed without having to apply for permission. I don't think this will be a problem tbh.

To answer your specific questions, it might not be that difficult to install another radiator attached to existing central heating. You may even be able to install a small boiler in this extension. A plumber or central heating engineer should be consulted to see what is possible.

Electric underfloor heating is doable, although it should not be installed under any shower tray, bath, toilet or cabinets. Being flexible it can be laid to avoid these areas so not a major issue.

Wet underfloor heating is also an option and would be a simple installation if you will be laying a new floor (which you probably will)

The building will almost certainly need to be cavity wall, or single skin and then insulated/boarded out.

Are there any drains/manholes where you propose to build this?

 

[Fazq01]

Hi,

Thanks for the advice. Calling it a conservatory is a rather complementary comment

I have access to drains via the side of the existing lean to, if I take it down and put in new footings, I will be too close to the boundry; I will need to run the drains under the new building instead.

What I planned was to make the 'new section' as a propper dewlling, with all the regs etc to comply with current standards, however try to insulate the existing structure as best as possible to continue to use it as an ocassional space.

I did consider a second small boiler to heat the bathroom and provide hot water, having a secondary source provides a bit of redundancy and could be benificial, I'll give it more thought as gas is readily availabe, but the Heating circuit is not. I've even crawled under the floor space of the existing house to see if I can pick up a line, but it's not an option without having to make cosmetic repairs.