My son is making a backyard deck of about 6 x 6 metres for my daughter. I am too old and doddery to help much, but am advising. Now we find that some of the planks (400 x 23 cm composite) are curved by up to 2mm, that is like a banana lying on its side.

The standard plank spacing is 5mm, and we have invisible clips for this. But if two adjacent planks happen to be curved the wrong way the gap could be up to 9mm at the centre of the planks, which will look horrible.

It seems that we must select planks as we lay them to minimise this effect, but it's not trivial to sort and reverse 4 metre planks, weighing 10+ kilos, to find the best fit. Most of the time my son will be working alone.

Does anyone have any tricks or advice to make life easier?

My son is making a backyard deck of about 6 x 6 metres for my daughter. I am too old and doddery to help much, but am advising. Now we find that some of the planks (400 x 23 cm composite) are curved by up to 2mm, that is like a banana lying on its side.

The standard plank spacing is 5mm, and we have invisible clips for this. But if two adjacent planks happen to be curved the wrong way the gap could be up to 9mm at the centre of the planks, which will look horrible.

It seems that we must select planks as we lay them to minimise this effect, but it's not trivial to sort and reverse 4 metre planks, weighing 10+ kilos, to find the best fit. Most of the time my son will be working alone.

Does anyone have any tricks or advice to make life easier?

Update 14 July: It turned out that we can (un)bend the planks with just a few kilos of force, applied with the knee. Thanks everyone for thinking along.

My son is making a backyard deck of about 6 x 6 metres for my daughter. I am too old and doddery to help much, but am advising. Now we find that some of the planks (400 x 23 cm composite) are curved by up to 2mm, that is like a banana lying on its side.

The standard plank spacing is 5mm, and we have invisible clips for this. But if two adjacent planks happen to be curved the wrong way the gap could be up to 9mm at the centre of the planks, which will look horrible.

It seems that we must select planks as we lay them to minimise this effect, but it's not trivial to sort and reverse 4 metre planks, weighing 10+ kilos, to find the best fit. Most of the time my son will be working alone.

Does anyone have any tricks or advice to make life easier?

My son is making a backyard deck of about 6 x 6 metres for my daughter. I am too old and doddery to help much, but am advising. Now we find that some of the planks (400 x 23 cm composite) are curved by up to 2mm, that is like a banana lying on its side.

The standard plank spacing is 5mm, and we have invisible clips for this. But if two adjacent planks happen to be curved the wrong way the gap could be up to 9mm at the centre of the planks, which will look horrible.

It seems that we must select planks as we lay them to minimise this effect, but it's not trivial to sort and reverse 4 metre planks, weighing 10+ kilos, to find the best fit. Most of the time my son will be working alone.

Does anyone have any tricks or advice to make life easier?