Q. Can one fix or replace a deck that will be used for the Suka and may also be dangerous in its current condition, during the Three Weeks?
A. Horav Shlomo Miller’s Shlit’a opinion is that one may fix it when necessary. However. when possible one should wait until after Tisha Beav.
Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a.