Seattle has local ordinances limiting the times that construction can be done for exactly this type of problem. Check the local code compliance web site to see if the work is properly permitted for after hours. If they are in violation, you can make a complaint with code compliance or object to any future permits.
If the contractors are working for your landlord, make a written complaint about the noise. Remind him of the quiet hours provided for in your lease. Your landlord has to follow those rules just as you do as a tenant. If the problem is within his control and he does not timely correct it, you have the right to terminate your lease early and move out.
The Landlord Tenant Act requires the Landlord to abide by city code on such issues. RCW 59.18.060 (1). The law also implies a covenant of "Quiet Enjoyment." But your remedy is probably to get out of your lease if the LL won't fix the problem. If you want to head that direction, make sure you provide the required notices and try to negotiate your way out so you don't get unfairly accused of breach.