hi derek if i was you i would foundation bricks instead of blocks they have been known to crumble in time bricks might be a little bit dearer but if a jobs worth doing it worth doing well.good luck.

Thanks Kennyboy, that was what I expected really, guess I,ll just have to dig a bit further into my pocket, thanks again. derekm

your welcome.

Sorry but you can buy any number of small greenhouses with an eves height of 7 foot! Where on earth have you been looking... small standard greenhouse is 7 foot high by 6 foot wide! Then they get bigger!

In my opinion 4inch dense concrete blocks will be fine but they're very heavy and don't look as well as bricks.
And unless you get concrete, or well burnt bricks ( or better still class 2 engineering bricks) they will get wet due to rising damp and possibly freeze and spall in Winter.

The blockwork will take less mortar and be more than twice as quick to build.

I've used good, dense clay bricks, stone faced bricks -(2months ago ! look for these at the builders merchants) and concrete blocks and each of these was adequate.

If the greenhouse is only 4 feet high then it is meant to be mounted on a solid wall of about three feet in height. Bricks are the traditional material for this wall and many exist that are a hundred years old and older. Concrete blocks would look ugly.

Although brick will look much better you should have no problem with dense blockwork as after all most houses are now built of them.

Thank you everyone for your comments, the greenhouse in question is a 12foot x 8foot {nominal}, but all the ones with high eaves , also had double doors and you just end up with a wider path, the 4 feet is to the eaves excluding the aluminium base, it is over 7 feet to the ridge, I just want to increase the eaves height for convenience, as I am 6 feet tall I don,t want to be banging my head on the glass. thanks again, derekm