Block Shed Insulation

Mr_Jailer

Hello,

Currently in the process of getting a single-skin concrete block shed built as follows:

1. It has a slanted roof with the rear higher than the front (3m vs 2.4m single pitch with apex in the middle)
2. It falls within 30 Sq metres regulation.
3. It will be made with single-skin concrete blocks.
4. The foundation will have 5cm insulation polystyrene.
5. The roof will be made of the 7 * 2 timber joists, with 18mm plywood sheets.
6. The roof will be covered with red hexagonal, felt shingles, except for a 3sq m portion towards one side which will be covered in acrylic sheets for daylight.
7. There will be a concrete block partition - but at maximum height of 2 metres. This will separate 'Shed' with 'Lounging / games area'. Both sections will have external doors.
8. The aim is to leave some of the internal blocks exposed 'as a feature' and perhaps painted.
9. The 2nd aim is to leave the timber roof exposed (perhaps treated) as an internal feature.
10. The 3rd aim is to utilise the perspex roof above the 'shed' section to work as a seasonal greenhouse (Spring).

My questions are:

A. How will having air bricks fitted help with the prevention of condensation?
B. What thickness of the acrylic sheets should be used on the roof, 6mm, 8mm or 10mm etc?
C. How best to insulate the external walls, bearing in mind, I'd like at least 2 of the internal walls of the 'Lounging' area to remain as brick features (the front and the partition wall).
D. Without eating too much internal space, what insulation options are there for both internal and external sides, (the front of the building, is intended to be slatted on the outside), with insulation in between, with some sort of wood effect cladding (PVC or timber slats etc.)).
E. One of the sides of the building is tight up against the neighbours block shed (close to the boundary line) maybe a 10cm gap. Because of the small gap and the likelihood of elements hitting the outside wall, is there a requirement to insulate that wall inside or out?

Any advice is appreciated, I'd like to fend off stale air and humidity being a factor in winter. I will be taking electrics into the building, and putting an electric heater on a timer is an option in winter.

Is there any precautions I should build into the building?

EachPenny

Mr_Jailer wrote: »

Is there any precautions I should build into the building?

Have you considered the need for planning consent and/or building regulations approval?

Furts

General observations are ...

The concept of single skin concrete blocks is potentially deadly, and will have zero insulation.

Even worse is the concept of 50mm polystyrene in the foundations.

Felt shingles and acrylic panels will be short term life - so future buyers will say "cheapskate".

The exposed timbers are a fire hazard.

I will leave the specifics to you.

Mr_Jailer

Thanks EachP, no planning permissions required, builder of 40 years has measured up + Building surveyor will visit property for house extension project.

Thanks Furts.

What I'm trying to achieve is a combination of the examples as attached.**

Thanks.

** How do I attach from PC?

Mr_Jailer

*t*ps://imgur.com/a/xyCaSMe - Link here, am a newbie, can not post links yet.

System

you're going to have to design a tardis to achieve the internal quality of space and the external dolls house look! If you are looking to insulate it, why are you going for a single block construction and then trying to figure out how to insulate it rather than starting from first principles of using the appropriate construction to create a habitable space with the features you want. The level of finish shown those imgur pics is not as straight forward as is looks

Mr_Jailer

Hi RSole,

Getting an extension done (side ground, double storey rear). The side of the house will be demolished but need to store the stuff somewhere, that's why I've opted to build a water-tight shed first (unfinished) to the roof level, with temporary plywood doors.

Once the extension is complete then will finish off the shed including glazing.

What I'd like to utilise the 2 segments of the shed are as follows:

"Shed" - Store Bikes, DIY tools, garden tools, bouncy castles, the 'dirty / mucky stuff' (mower)'

"Lounge" - Just Lay out a carpet, with bean bags dotted around, hook up a projector on a rafter and point it at one one of the walls, place to chill on a hot day, use the space to play games, toys etc. Underlay / carpeting is an option.

In the winter, neither will hardly get any use, so the "lounge" may be used for storing, say garden tables and chairs.

In terms of inhabitable use, it will only extend the garden space, our garden is south facing, the blocks interior will give a cool shade from the summer heat (or will it?) but with the amount of sun we get is negligible. I don't see it being habited for more than a month total a year.

This building is being constructed on raised concrete foundation at the back of the garden, the previous owner started something as when the builder ripped the slabs apart there was DPM but no insulation.

I've just re-purposed that space to finish off what the previous owner started but to my multl-function specs - I'm only going to have the opportunity to create and design something different from flat packed off eBay buildings probably once in my life.

That said I didn't want double skin walls because it will eat into the garden and to the shed. To preserve it what I may do is this (after extension is complete and permanent homes have been found for the stuff):

Rear Outside Wall: Use Thompsons One-Coat Water Sealant.
Rear Interior Wall: Dot and Dab polystyrene / drywall and skim.

Right Outside Wall: Use Thompsons One-Coat Water Sealant.
Right Interior Wall: Dot and Dab polystyrene / drywall and skim.

Front Outside Wall: Dot and Dab polystyrene between Slats (or battens) and screw timber facia panels or western red cedar battens horizonatly across it to match the adjacent garden fences (depending on budget at the time).
Front Interior Wall: Paint / Stain using maisionary paint for a feature wall.

Left Outside Wall: Do nothing as its tight up against the boundary (neighbours block shed).
Left Interior Wall: Undecided as there will be concrete pillars spaced out with slots sliced out to put shelves flush against the wall.

Internal partition wall: Do nothing on Shed side but create a Feature wall, paint / stain on "Lounge" side.

That's the design, a combination of internal and external insulation methods, I'm hoping will avoid condensation / stale air problems in winter as don't don't to ruin whatever is stored in Winter.

EachPenny

Mr_Jailer wrote: »

Thanks EachP, no planning permissions required, builder of 40 years has measured up + Building surveyor will visit property for house extension project.

When you say that, have you looked in depth into all the planning requirements, or just had a quick look at the permitted development guidance?

If you are also having an extension built you will be getting multiple visits from the Council.... your 'shed' may also have an adverse impact on your plans for an extension.

How does your neighbour feel about having your building (with ii's attendant fire risks) within 100mm of theirs? Are they likely to object and kick off?

Mr_Jailer

Hi EachP,

Neighbour to the left already has a block shed built just along our boundary line at the back of their garden.

Neighbour at the back of the garden (Road End House) is a builder, I told him about my intentions, and got a quote off him, but he didn't get back to me. He said building a block shed would save him from having to put a fence up, but wanted me to render / paint it to make it look aesthetically pleasing to him. Also, they had planned to extend their ground floor rear out coming into our eye line

Note: The concrete foundations three brick high were already laid for such a building by a previous owner in the same position, I've used it for a BBQ once or twice but its more me having to clean up the leaves, though I have cut the nearest over hanging branches down.

Neighbour on the right has several trees at the back of their garden, branches overhanging our garden, and that is more of a problem for us neighbours than the shed will be to them.

This shed will replace a metal Apex shed at the side of the garden next to left neighbour and also the attached side-building area which will be demolished.

It's a block shed, walls are high-density concrete blocks and the roof will be made of 7 * 2 rafters and 18mm Plywood. The Asphalt shingles are fire retardant and won't help the spread of fire.

The neighbours trees are more likely to catch fire.

The building inspector will pop down periodically to inspect the extension and will see the shed, if any questions arise, I will show him photographs of the intentions of the previous owner and I continued on from that, though the height at the eaves are below 2.5m and less than 30 Sq. M, there won't be anyone sleeping in there, and if there is still a doubt, he can see the neighbours shed on the left.

Supposing it is a sound plan, I still have to think about insulation methods before the end of autumn.

Mr_Jailer

Hello,


The Single-skin block shed is up, made with solid 7.3N Blocks.


Previously I've mentioned the following:


---

Previously: "Rear Outside Wall: Use Thompsons One-Coat Water Sealant.
Rear Interior Wall: Dot and Dab polystyrene / drywall and skim."


Now I'd like:

Rear Outside Wall: - Paint with Black Bituminous waterproofing paint. This should repel water instead of seeping into block and leaving wet patches inside.
Rear, and the 2 sides of the Interior Walls: - Batten at 40cm centers with treated 25 x 50mm battens.


Now I am in need of technical guidance here, I've read up how moisture and condensation build up works, but need a solution for my particular scenario in terms of insulating the inside of the 3 walls:


Layers From Outside - In:


1. Bitumen Waterproof Sealant.
2. 7.3 Kn 100mm Concrete Block.
3. Breathable waterproof (roof felt) tacked directly onto the Block with the waterproof layer end against the block.
4. Treated timber battens screwed into the felt / blocks (80mm hammer fixing screws).
5. 25mm thick Polystyrene Insulation planted between the battens.
6. Plasterboard screwed into the battens.


There is no air gap in this scenario, the 25mm insulation will sit flush with the 25mm batten, pressed in by the 12.5mm plasterboard.



Is an air gap needed is this scenario or should this setup just work?



Any technical advise / detailed alternative suggestions is appreciated.


Thanks,


MJ.

armchaireconomist

25mm polystyrene against a single skin concrete block doesn't sound like anything i'd want to put a "lounge" in.


Also, not much point in your breathable membrane if you're going to slap a load of bitumen on the outside.