How wide can joints be in mortar for dwarf wall greenhouse

kingandy2nd · 2 Aug 2020

Kind of a how long’s a piece of string question, as depends on the rain strength, direction, etc.

I put strips of 450mm wide DPM plastic over my cavity wall (held down with bricks) and that gives it protection

I’ve laid bricks in the light rain, and been caught out and had sudden downpours as I’m laying.

I think providing the mortar is dry enough and/or the rain gentle enough to not wash out the joints you’ll be fine as long as the top is covered when it does rain.

JohnD · 2 Aug 2020

Mortar gains strength by being damp. If you cover it at the end of the day, by morning it will be hard enough to withstand rain.

It will actually be stronger in dull, drizzly weather that prevents it drying too fast. Hot sunshine will make it weak and crumbly. Once it has dried it stops gaining strength.

Eamman · 2 Aug 2020

JohnD said:
Mortar gains strength by being damp. If you cover it at the end of the day, by morning it will be hard enough to withstand rain.

It will actually be stronger in dull, drizzly weather that prevents it drying too fast. Hot sunshine will make it weak and crumbly. Once it has dried it stops gaining strength.

So,how can you tell if it's strong enough?

JohnD · 2 Aug 2020

If you can snap it with your fingers, or scratch it with your fingernails, it's not.

Kept damp for a few days will be fine. It will change colour as it dries

After the first day, rain will not hurt it.

Nige F · 2 Aug 2020

JohnD said:
Mortar gains strength by being damp. .

As once said in Germany KDF - Kraft Durch Feuchtigkeit

stuart45 · 2 Aug 2020

Never learnt more than 'einer bier bitte' when I worked over there.

Eamman · 7 Aug 2020

JohnD said:
Mortar gains strength by being damp. If you cover it at the end of the day, by morning it will be hard enough to withstand rain.

It will actually be stronger in dull, drizzly weather that prevents it drying too fast. Hot sunshine will make it weak and crumbly. Once it has dried it stops gaining strength.

Ok! This has been bugging me all week! How do you tell if the mortar has dried too fast, I mean, it's still going to go hard, so how does one tell?

JohnD · 7 Aug 2020

if it dries too fast, it is not as hard or as strong, and never will be.

Next time you have some mix, leave a blob on rag or newspaper, in the sun, so that it dries out with in hour or two (or overnight if you prefer

Or build a south-west facing wall on a hot sunny day, where the sun will come on to it at noon and shine on it during the afternoon.

Tomorrow, or in ten years time, you will be able to scrape the mortar out with your fingernail.

Then dig out a fencepost or drain that has been buried in damp soil for 50 years, and try to break the concrete with a hammer. it will be surprisingly hard.

https://www.cement.org/learn/concrete-technology/concrete-construction/curing-in-construction

Eamman · 7 Aug 2020

JohnD said:
if it dries too fast, it is not as hard or as strong, and never will be.

Next time you have some mix, leave a blob on rag or newspaper, in the sun, so that it dries out with in hour or two (or overnight if you prefer

Or build a south-west facing wall on a hot sunny day, where the sun will come on to it at noon and shine on it during the afternoon.

Tomorrow, or in ten years time, you will be able to scrape the mortar out with your fingernail.

Then dig out a fencepost or drain that has been buried in damp soil for 50 years, and try to break the concrete with a hammer. it will be surprisingly hard.

https://www.cement.org/learn/concrete-technology/concrete-construction/curing-in-construction

Eamman · 7 Aug 2020

If it dries too fast will it be a different color the next day? Or will it be difficult to tell visually compaired to a slow drying brick?

Eamman · 3 Sep 2020

After laying the engineering bricks 2 courses,I'm now using a faux reclaimed brick but,I'm struggling with them very porous ,and mix goes off very quickly, and suggestions?

Eamman · 13 Oct 2020

Going to leave this here a while and tell me what you think,I hope I did reasonably ok! It's 15" High!

kingandy2nd · 13 Oct 2020

Good work! Is there a DPC?

Eamman · 13 Oct 2020

Yes,I'm using the engineering bricks as My DPC 2 courses! It's my first time doing this, and was told Engineering brick can be used for this hoping the mortar is hard enough,I certainly won't be tearing it down,I will have to take a gamble at this stage!

Eamman · 13 Oct 2020

What's the minimum foundation one can put on this, just curious?

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How wide can joints be in mortar for dwarf wall greenhouse

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