ᐅ How to Calculate the Amount of Mortar and Ytong Blocks Needed?

Hello,
suppose you want to build a small garden shed measuring 6m x 4m (and 2.40m (7 ft 10 in) in height – without the roof yet) on an existing base slab using Ytong blocks (Ytong plan blocks 499 x 365 x 249 mm (19.6 x 14.4 x 9.8 inches)) and later install a roller shutter door (2632 x 2405 mm (103.6 x 94.7 inches)) and a window (50 x 100 cm (20 x 39 inches)).

Questions:
- How do I calculate, for example, how much mortar and Ytong blocks I will need? I would have to take into account the thickness of the mortar joints.
- How large should the door and window openings be after building the walls to properly install the door and window? Would it make sense to add about 2-3 cm (1 inch) extra clearance for sealing work?

Check the manufacturer’s specifications.
Each mortar (or adhesive) lists its coverage.
There are also installation instructions for the window and door.
The number of bricks is determined by the openings.

However, some materials are still missing: concrete and steel for the ring beam, roof and drainage, moisture barrier...

And really 36.5cm (14 inches) Ytong? Isn’t that a bit much?

Thank you first for the response.
I had been considering between aerated concrete blocks (Ytong) and sand-lime bricks. Sand-lime bricks seem to be more challenging to work with. Aerated concrete is comparatively easier. Since the garage will be built directly on the neighbor’s boundary (corner area of two neighbors) and might also be used for some woodworking such as sawing and drilling inside, I wanted to choose a block with a somewhat higher density (for better sound insulation). That’s why I am currently leaning towards the 36.5cm (14.4 inches) version. I think it will also be easier to drill into later for mounting shelves or similar.

I intend to hire a roofer separately for the roof. I only feel confident to do the masonry myself if I thoroughly study and research it.

You lose almost about 80cm (31 inches) in width and length just by using ytong blocks; it’s better to choose 17cm (7 inches) calcium silicate bricks instead, as they provide better sound insulation and can support shelves.

Thanks for the advice. However, isn’t sand-lime brick more difficult to work with and harder to cut? Basically, I didn’t want to buy expensive saws costing around 300 EUR (about $320) that I might never use again ^^ If you say sand-lime brick is definitely preferable to Ytong and the 300 EUR cost (which isn’t that much overall) is justified considering the number of bricks, then I’m happy to reconsider.

17.5 cm (7 inches) should be enough. Using 24 cm (9.5 inches) blocks is probably overkill for the requirements, right? I ask because I only want to build this once in my life, and I don’t want to have to add an exterior wall later due to insufficient stability.

Calcium silicate brick has exactly the properties you need...

Structurally and acoustically better.
Space-saving.

The few extra minutes of effort should definitely be worth the later gain of 3.5 m² (38 sq ft) of space?!
And you save on expensive adhesive anchors when using calcium silicate brick...