A regular expression was the best way I've found so far
<p:inputText id="numInput" value="#{val.value}" required="true"
label="#{val.title}" validatorMessage="Not valid Number">
<p:ajax event="change" process="@form" update=":edit_main" />
<f:validateRegex pattern="^[-+]?[0-9]*\.?[0-9]{1,2}+$" />
</p:inputText>
<p:message for="numInput" />