sealing greenhouse gaps

thanks to all for your advice

Kristen
"Gaps around the joins" - is that where the poly-carb meets the frame?yes mainly in the corners

I think the best answer to that might be some silicon [or perhaps a rubberised adhesive] out of one of those tubes that you put in a gun-like arrangement. thanks

But ... I'm not a fan of poly-card. Light weight, so manufactures can use lighter-weight frames, the wind over the surface exerts negative pressure, same way air over an aircraft wing "lifts" it, and the sheets "pop out".
husband bought it for me as a treat ! he went for the poly one as my neighbours Glass one gets battered ever year with the wind off the coast here and we have only small garden with 5 young grandchildren so safety was a big factor. You are so right about the roof sheets popping out..... lost the roof first winds we had, luckily all sheets were not damaged and stayed in next doors garden, so have re fixed that but used "Z" clips to hold firm and where there was a small gap between poly and frame i have run a bead of draught excluder, which has worked a treat, no movement at all when the weather was wind a few weeks back, i have added a vent in the back wall and have fitted an auto window opener .... was unsure about the roof vents

Julie ..... i think your answer was the best

 

"5 young grandchildren so safety was a big factor"

Ah ... can't argue with that building a glass greenhouse at the bottom of the hill that the kids Bike and Skateboard down is never a good plan !

Silicone:

No Nonsense GP Silicone Clear 310ml | Screwfix.com

and a gun to fit:

Trade basics Sealant Gun | Screwfix.com

Tape-up-the-cracks:

Corotherm Ariel Aluminium Sealing Tape Silver 45mm x 10m | Screwfix.com

Well something like those ... these aren't intended as specific recommendations, I just went to Screwfix site to get some example images, but they have obfuscated them so I can't link to them ... in fact I dunno why I'm promoting Screwfix at all if they feel like that about me giving a link to their site via their images!!; anyways I haven't got time just now to spend the 5 minutes it would take to work around their cloaking and I'm too lazy to look at another site ... so I suppose they have won :(

Edit:

Actually I will, just to show how futile their cloaking attempt is:

 

i actually have silicon and gun here just need to tape now thanks for all help

BUT i will wait for a warmer dry day to do it BBBBBBBBBBBBBRRRRRRRRR

Kristen thanks for effort of going around the cloaking effect

 

But you don't want the Gun and Silicone, so I've got to take them back now ...