Re-jointing a patio - are expansion joints needed?

WobblyDog

I've just re-jointed a tatty old patio using a standard mortar mix. It's about 8 metres by 3 metres, and the slabs are concrete, about 60cm square and 3cm thick. The slabs are laid on a bed of sand. At each of the far ends the patio meets a brick wall. In other words, there's an 8m length of slabs and mortar between the walls.

Should I have done something to allow for expansion of the slabs in the summer? Is there any risk of the walls being disturbed by the sun-heated slabs pushing against them? Or do I need to find something more important to worry about?

matty2767

In a commercial trafficked scenario you would have an expansion joint around all obstructions and alongside buildings and you wouldn't mix rigid joints with flexible bedding. Your case is obviously different, but if it boils down to your piece of mind you could scrape out the joints which abut the walls (3m + 3m if I understand your description) and insert some flexible board. You would need to put something back otherwise debris will collect in the joint and effectively you would be back to where you are now.

How wide are your joints between slabs?

WobblyDog

The joints vary between about 5mm and 20mm (it's a fairly scruffy old patio).

phill99

I can't help thinking you are completely over engineering this.

pmartin86

As Phill99 says, your probably over engineering this, I'm NOT an expert, but id probably be comfortable with the standard 10mm "grout" gap between slabs and wall, I honestly cant see slabs expanding that much in heat...