We had all new windows installed by this builder in November 2000. Since that time , we have had seal failure on 5 or 6 windows. It has usually taken 2-3 months from initial message left to company to replacement of windows (on lifetime guarantee.) To this point, the manufacturer , Allside, has replaced the windows. Per their warrantee, I am responsible for installation of replacements. I do not know why we continue to have problems with seal failures, but please be aware of this problem before purchasing.