Doors and Windows - How to install Aluminum Storm Doors in opening 31

I want to install an aluminum storm door in an outside entrance to an apartment in the northeast. The door frame opening is 31" x 80".

hi jbrogan,First go to a home improvement center (Lowes,Home depot,etc.)Pick out the door you want,they come in standerd sizes,30X80,32x80,and 36x80.Since your rough opening is 31x80,you need the 30x80 door.I know lowes used to sell Larson doors but now there selling Pella.Buy a good quility door if you can afford to.A soild wood core,vinyl clad is your best bet.As far as installing the door,as long as your rough opening is level and plum just follow the instrutions,and you should be able to install it.If your rough opening is out of square,the job could turn into a nightmare for you if you dont know what your doing.One more thing,make sure you have at least 1" from the entry door doorknob to the end of the jam.If you dont have that clearance,you have to pack out the rough opening to get that clearance to hang the door.

Thanks for the information.