Sloping sides help with wind resistance, but reduce the growing volume, especially at the sides. The 6-8 almost certainly refers to the dimensions of the base, not the top. You may only be able to fit a 3'x6' work table in the center of the house. One with straight sides would probably allow two 2'x8' tables on the sides, without needing to crouch to get past them.

Definitely straight sided if you want t be able to stand up in easily, also get the biggest greenhouse you can afford that will fit in the space you have.

Thank you both.

Tug - in the UK we rarely have central work tables - I'll be going for staging (slatted wooden shelving) on each side.

Mg - yes, I agree with you, and I loved my 10' x 8' in the last house. But now that we have moved to a smaller house and garden, the 8' x 6' will fit better.

Presumably the 6x8 refers to the base. The advantage of a sloping side one is to give you more floor space but for that size the resulting reduced area at bench height would be a drawback.

Thank you Sue. Well, I won't be needing more floor space, so will probably go for a straight-sided one.

Sorry, Sheila! I'm recovering from flu, so my thoughts are even more scrambled than usual. I was thinking that with sloping sides, plants on side tables would soon be bumping against the cold glass--not much of a factor with seedlings and cuttings, like you said you were doing!

Hope you'll soon be feeling better Tug!

Hi Sheila. Is the sloping an "A frame" style? I prefer the pitched roof because I'm tall and don't like bumping my head. I think it's better for collecting rain water.

Hi Paul. Not necessarily. I’m talking about the sides from the gutter down. I’m quite tall too, but have never had a problem with head space in a greenhouse. But thanks for joining in :)

OK the only advantage I can think of to sloping sides is that the lower trays of seed will get better lighting.