b"The plywood or other exterior grade material needsonly to be 1/8 - 1/4 thick. The level of the sillshould be checked when the opening is measured so the addition of the plywood can be determined tobe necessary and its thickness can be accommodatedin the sizing of the new window.Installation of the Undersideplywood should be adequately caulked of Sliderunderneath with a bedding sealant, andthe plywood should be covered whencapping the finished installation on theoutside.2. The Opening Must Be Square. Because there is no gravity to help the sash operate smoothly, thesquareness of the opening is more important for aslider so that the operating sash do not bind up. Be careful to install the slider in a relaxed state.ProperDon't push the window against the blindstop or Sash/Frameanchor to the opening in a manner that might force Reveal the window to rack or twist. must have A equal B Other considerations when installingand theSliding Windows. window A. The sill must have uniform support acrossplumb andthe whole sliding window, and the support mustsquare be greater than the width of the tracks.B. Any exterior finish work must not cover norimpede the operation of any weep holes which allow drainage of any accumulated water from theoperating tracks.C. No anchor screws should be put through thesill/track of a slider. This may cause water to getunder the window and cause water damage to theopening or leak in the house. D. Be sure that the full perimeter of the windowSeal theis adequately insulated under the master frame. ExteriorNOTE: Further information that will be helpful in installing but do notSliding Windows is found in this book in the sections on cover theFrame-Out Method for Replacing Old Aluminum and Wood weep holesWindows, and Installing Windows in Masonry Openings.Window Fitters Guide to Window Installation582020 AWDI, LLC Do not reproduce without permission"