How do i determine the height of new walls?

[carlosdeanos]

Hello, I am just starting out on a single storey extension on my bungalow. At the moment I am trying to gather specs for each stage I can work from.

 

Can anyone help me with how I can determine the height for the external walls? It will be block internal and external, with external render. I will have a flat fibreglass warm roof.

 

Any help appreciated. Carl.

[Moonshine]

Room heights are typically 2.4m, and a flat roof probably allow for 0.5m, so you are looking at circa 2.9m to the top of the roof, also account that the roof has to have a 1:40 slope.

[carlosdeanos]

So yes my current ceiling are 2.4m, so is 2.4m where the top of the highest course of blocks should finish on the new wall? Thanks.

[Declan52]

It will depend on what way you'll finish the outside. Are you going for facia boards for example.

[Carrerahill]

Starting out as in, building it or planning it?

 

If planning stage then usually work out chamber height then work up through the layers to see where that gets you, in our extension we had to work from the lead flashing down! I wanted to make the most of the height available to us to maximise internal ceiling heights. I then made the eaves of the roof as high as I could while maintaining an adequate pitch for the roof tiles I wanted to/had to use.

 

The thing that would drive me initially in determining a wall height would be to get the existing building plan, know the existing building ceiling heights (if you want to copy those) and then draw some vertical lines across at various levels to determine where the roof abutment would be, or a max ridge height or a gable etc. depending on the orientation of the existing and proposed. I would then ascertain ground level, and finished floor level (FFL). At that I could then check the spaces available to me permit required roof pitch and that windows and doors will then fit suitability. That is a 10-15 minute basic task which is where most people involved in planning would start. There is little point in doing much else until the basics check out! 

 

I think it is things like this that sometimes people forget or don't understand which can lead to big mistakes if you try and DIY something you have little knowledge of. We had friends try and copy what I did, they ended up building an extension where the ceiling was going to end up lower than standard door height... He had not allowed for the height of his lintels when he worked it all out, so when he dropped the heights for the lintels, the lintel was going to come in about 1800mm so that his roof height remained untouched.

Edited February 6, 2020 by Carrerahill

[carlosdeanos]

@Declan52 For the finish I was hoping to have a small 'lip' type overhang that I can possibly have lights in. But essentially a facia it think.

 

@Carrerahill the lines is a good idea thanks. I will also make a note I need to consider the plasterboard and finish to make it level with existing.

 

Thanks.