Grammar
 

　一ヶ月前隣に引っ越してきた家族の、度し難いまでの 浅慮さを除けばだが。
　　　ichikagetsu mae tonari ni hikkoshite kita kazoku no, doshigatai made no senryo sa wo nozokeba daga.

I was wondering what's with the さ（sa) 浅慮さ(senryo sa)

you can add "さ（sa）" to the stem of adjective and use it as a noun,or changed into a noun.
When adjective change into noun, the rest except for the stem is delited.
by the way,When whose tense change is so.

明る（akaru）;the stem of adjective

The examples are as follows:
明るい（akarui）;adjective→明るさ（akarusa）；noun→明るか った（akarukatta）;the past
暗い（kurai）→暗さ（kurasa）;noun→暗かった(kurakatta);the past

but 浅慮 is already a noun.....

the meaning of "浅慮"　is that a man is a man of thoughless about things,which means that "浅慮” expresses nature of man,something or things.
That is to say,"浅慮” is near to adjective as for the meaning of it.
That is why you can add "sa" to it as a termination.

On the other hand,the nouns such as "犬";inu and "箱";hako are perfectly different from adjective.
→犬さ×、箱さ×

Ok, I understand now, thx~